U.S. patent application number 13/054391 was filed with the patent office on 2011-06-09 for aqueous polyurethane resin dispersion and process for preparing the same.
Invention is credited to Masahiro Naiki, Taku Nakamura, Manabu Takahashi.
Application Number | 20110136976 13/054391 |
Document ID | / |
Family ID | 41550284 |
Filed Date | 2011-06-09 |
United States Patent
Application |
20110136976 |
Kind Code |
A1 |
Nakamura; Taku ; et
al. |
June 9, 2011 |
AQUEOUS POLYURETHANE RESIN DISPERSION AND PROCESS FOR PREPARING THE
SAME
Abstract
This is to provide an aqueous polyurethane resin dispersion
which can form a tough coating film. An aqueous polyurethane resin
dispersion is obtained by dispersing an aqueous polyurethane resin,
which is obtained by reacting (A) a polyurethane prepolymer
obtained by reacting (a1) a polycarbonate polyol having no urethane
bonding having an average molecular weight of 400 to 5000, and
having 2.05 to 5 hydroxyl groups in average in one molecule, (b) a
polyol compound having an acidic group and (c) a polyisocyanate, or
obtained by reacting (a2) the polycarbonate polyol having no
urethane bonding having an average molecular weight of 600 to 5000,
and having 2.05 to 5 hydroxyl groups in average in one molecule,
and having an acidic group, and (c) a polyisocyanate, and (B) a
chain elongating agent having a reactivity with the isocyanate
group of (A) the polyurethane prepolymer, being dispersed in an
aqueous medium.
Inventors: |
Nakamura; Taku; (Yamaguchi,
JP) ; Naiki; Masahiro; (Yamaguchi, JP) ;
Takahashi; Manabu; (Yamaguchi, JP) |
Family ID: |
41550284 |
Appl. No.: |
13/054391 |
Filed: |
June 30, 2009 |
PCT Filed: |
June 30, 2009 |
PCT NO: |
PCT/JP2009/061892 |
371 Date: |
January 14, 2011 |
Current U.S.
Class: |
524/839 |
Current CPC
Class: |
C08G 18/6659 20130101;
C09D 175/06 20130101; C08G 18/12 20130101; C08G 18/12 20130101;
C08G 18/44 20130101; C08G 18/3228 20130101; C08G 18/758 20130101;
C08G 18/0823 20130101 |
Class at
Publication: |
524/839 |
International
Class: |
C09D 175/04 20060101
C09D175/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 16, 2008 |
JP |
2008-184574 |
Jul 16, 2008 |
JP |
2008-184575 |
Claims
1. An aqueous polyurethane resin dispersion which comprises an
aqueous polyurethane resin obtained by reacting (A) a polyurethane
prepolymer obtained by reacting (a1) a polycarbonate polyol having
no urethane bonding, (b) a polyol compound having an acidic group,
and (c) a polyisocyanate, and (B) a chain elongating agent having a
reactivity with the isocyanate group of the (A) polyurethane
prepolymer, being dispersed in an aqueous medium, and (a1) the
polycarbonate polyol has a number average molecular weight of 400
to 5000, and has 2.05 to 5 hydroxyl groups in average in one
molecule.
2. The aqueous polyurethane resin dispersion according to claim 1,
wherein (A) the polyurethane prepolymer is a material obtained by
reacting (a1) a polycarbonate polyol having no urethane bonding,
(a') a polycarbonate diol, (b) a polyol compound having an acidic
group, and (c) a polyisocyanate, where (a1) the polycarbonate
polyol has a number average molecular weight of 400 to 5000, and
has 2.05 to 5 hydroxyl groups in average in one molecule.
3. The aqueous polyurethane resin dispersion according to claim 1,
wherein (a1) the polycarbonate polyol is a material obtained by
reacting a diol compound, one or more polyol compounds selected
from a triol compound, a tetraol compound and a pentaol compound,
and a carbonate compound.
4. The aqueous polyurethane resin dispersion according to claim 1,
wherein (a1) the polycarbonate polyol is a material obtained by
subjecting a polycarbonate diol, and one or more polyol compounds
selected from a triol compound, a tetraol compound and a pentaol
compound to transesterification reaction.
5. An aqueous polyurethane resin dispersion which comprises an
aqueous polyurethane resin obtained by reacting (A) a polyurethane
prepolymer obtained by reacting (a2) the polycarbonate polyol
having no urethane bonding and (c) a polyisocyanate, and (B) a
chain elongating agent having a reactivity with the isocyanate
group of (A) the polyurethane prepolymer, being dispersed in an
aqueous medium, and (a2) the polycarbonate polyol has a number
average molecular weight of 600 to 5000, has 2.05 to 5 hydroxyl
groups in average in one molecule, and has an acidic group.
6. The aqueous polyurethane resin dispersion according to claim 5,
wherein (A) the polyurethane prepolymer is obtained by reacting
(a2) the polycarbonate polyol having no urethane bonding, (a') a
polycarbonate diol and (c) a polyisocyanate, and (a2) the
polycarbonate polyol has a number average molecular weight of 600
to 5000, has 2.05 to 5 hydroxyl groups in average in one molecule,
and has an acidic group.
7. The aqueous polyurethane resin dispersion according to claim 5,
wherein (a2) the polycarbonate polyol is a material obtained by
subjecting a polycarbonate diol containing an acidic group obtained
by reacting a polycarbonate diol and (b) a polyol compound having
an acidic group, and one or more polyol compounds selected from a
triol compound, a tetraol compound and a pentaol compound to
transesterification reaction.
8. A process for preparing an aqueous polyurethane resin dispersion
which comprises the steps of: Step (.alpha.1) of reacting (a1) a
polycarbonate polyol having no urethane bonding, (b) a polyol
compound having an acidic group and (c) a polyisocyanate to obtain
(A) a polyurethane prepolymer, Step (.beta.) of neutralizing the
acidic group of (A) the polyurethane prepolymer, Step (.gamma.) of
dispersing (A) the polyurethane prepolymer in an aqueous medium,
and Step (.delta.) of reacting (A) the polyurethane prepolymer and
(B) a chain elongating agent having a reactivity with the
isocyanate group of (A) the polyurethane prepolymer to obtain an
aqueous polyurethane resin, wherein (a1) the polycarbonate polyol
has a number average molecular weight of 400 to 5000, and has 2.05
to 5 hydroxyl groups in average in one molecule.
9. The process for preparing an aqueous polyurethane resin
dispersion as according to claim 8, wherein Step (a 1) to obtain
(A) the polyurethane prepolymer is a step of obtaining (A) a
polyurethane prepolymer by reacting (a1) a polycarbonate polyol
having no urethane bonding, (a') a polycarbonate diol, (b) a polyol
compound having an acidic group, and (c) a polyisocyanate, where
(a1) the polycarbonate polyol has a number average molecular weight
of 400 to 5000, and has 2.05 to 5 hydroxyl groups in average in one
molecule.
10. A process for preparing an aqueous polyurethane resin
dispersion which comprises the steps of: Step (.alpha.2) of
reacting (a2) a polycarbonate polyol having no urethane bonding and
(c) a polyisocyanate to obtain (A) a polyurethane prepolymer, Step
(.beta.) of neutralizing an acidic group of (A) the polyurethane
prepolymer, Step (.gamma.) of dispersing (A) the polyurethane
prepolymer in an aqueous medium, and Step (.delta.) of reacting (A)
the polyurethane prepolymer and (B) a chain elongating agent having
a reactivity with the isocyanate group of (A) the polyurethane
prepolymer to obtain an aqueous polyurethane resin, wherein (a2)
the polycarbonate polyol has a number average molecular weight of
600 to 5000, has 2.05 to 5 hydroxyl groups in average in one
molecule, and has an acidic group.
11. The process for preparing an aqueous polyurethane resin
dispersion as according to claim 10, wherein Step (.alpha.2) to
obtain (A) the polyurethane prepolymer is a step of reacting (a2)
the polycarbonate polyol having no urethane bonding, (a') the
polycarbonate diol, and (c) the polyisocyanate to obtain (A) a
polyurethane prepolymer, where (a2) the polycarbonate polyol has a
number average molecular weight of 600 to 5000, has 2.05 to 5
hydroxyl groups in average in one molecule, and has an acidic
group.
12. The process for preparing the aqueous polyurethane resin
dispersion according to claim 8, wherein Step (.beta.) and Step
(.gamma.) are carried out simultaneously.
13. The process for preparing the aqueous polyurethane resin
dispersion according to claim 8, wherein Step (.gamma.) and Step
(.delta.) are carried out simultaneously.
14. A coating composition containing the aqueous polyurethane resin
dispersion according to claim 1.
Description
TECHNICAL FIELD
[0001] The present invention relates to an aqueous polyurethane
resin dispersion in which a polyurethane resin is dispersed in an
aqueous medium, and process for preparing the same and a coating
composition containing the same. The aqueous polyurethane resin
dispersion of the present invention can be widely utilized as a
starting material for a paint or a coating agent, etc.
BACKGROUND ART
[0002] A polycarbonate polyol is a useful compound as a starting
material for preparing a polyurethane resin which is used for
preparing a hard foam, a soft foam, a paint, an adhesive,
artificial leather, ink binder etc., by the reaction with an
isocyanate compound.
[0003] Also, it has been known that a coating film obtained by
coating an aqueous urethane resin dispersion which uses a
polycarbonate polyol as a starting material is excellent in light
resistance, heat resistance, hydrolysis resistance and oil
resistance (see Patent Literature 1).
[0004] It has been proposed to obtain a urethane prepolymer having
high water dispersibility by using, as polyol components of an
aqueous urethane resin dispersion, a mixed polyol comprising a diol
and a low molecular weight triol and reacting with an isocyanate
(see Patent Literatures 2 and 3).
PRIOR ART REFERENCES
Patent Literature
[0005] [Patent Literature 1] JP H10-120757A [0006] [Patent
Literature 2] JP H3-174429A [0007] [Patent Literature 3] JP
H8-193181A
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0008] However, when a low molecular weight triol is present in
much amount in the reaction to produce a urethane prepolymer,
urethane bondings are accumulated at the branched portions by the
triol according to the reaction of a low molecular weight triol and
an isocyanate compound, whereby a portion having high density of
urethane bondings occurs in the molecule.
[0009] When the polyurethane resin dispersion obtained by using a
urethane prepolymer which has a portion having high density of
urethane bondings is used as a starting material for a paint or
coating agent, hydrogen bond is formed at the portion at which
urethane bondings are accumulated, so that hardness can be
revealed. However, packing of the whole molecule is disturbed so
that there are problems that film-forming property is poor and
uniform coating film can be difficultly obtained, and cracks likely
occur at the resulting coating film.
Means to Solve the Problems
[0010] The present inventors have carried out various
investigations to solve the above-mentioned problems, and they have
found that a polyurethane prepared by using a prepolymer obtained
by reacting a specific polycarbonate polyol and an isocyanate gives
good film-forming property and a tough coating film can be obtained
because accumulation and localization of urethane bonding is
inhibited, whereby the present invention has been accomplished.
[0011] The present invention is more specifically as mentioned
below.
(1) an aqueous polyurethane resin dispersion which comprises an
aqueous polyurethane resin obtained by reacting (A) a polyurethane
prepolymer obtained by reacting (a1) a polycarbonate polyol having
no urethane bonding, (b) a polyol compound having an acidic group,
and (c) a polyisocyanate, and (B) a chain elongating agent having a
reactivity with the isocyanate group of the above-mentioned (A)
polyurethane prepolymer, being dispersed in an aqueous medium, and
the above-mentioned (a1) polycarbonate polyol has a number average
molecular weight of 400 to 5000, and has 2.05 to 5 hydroxyl groups
in average in one molecule; (2) the aqueous polyurethane resin
dispersion described in (1), wherein (A) the polyurethane
prepolymer is a material obtained by reacting (a1) a polycarbonate
polyol having no urethane bonding, (a') a polycarbonate diol, (b) a
polyol compound having an acidic group, and (c) a polyisocyanate,
where the above-mentioned (a1) polycarbonate polyol has a number
average molecular weight of 400 to 5000, and has 2.05 to 5 hydroxyl
groups in average in one molecule; (3) the aqueous polyurethane
resin dispersion described in (1) or (2), wherein (a1) the
polycarbonate polyol is a material obtained by reacting a diol
compound, one or more polyol compounds selected from a triol
compound, a tetraol compound and a pentaol compound, and a
carbonate compound; (4) the aqueous polyurethane resin dispersion
described in (1) or (2), wherein (a1) the polycarbonate polyol is a
material obtained by subjecting a polycarbonate diol, and one or
more polyol compounds selected from a triol compound, a tetraol
compound and a pentaol compound to transesterification reaction;
(5) an aqueous polyurethane resin dispersion which comprises an
aqueous polyurethane resin obtained by reacting (A) a polyurethane
prepolymer obtained by reacting (a2) a polycarbonate polyol having
no urethane bonding and (c) a polyisocyanate, and (B) a chain
elongating agent having a reactivity with the isocyanate group of
the above-mentioned (A) polyurethane prepolymer, being dispersed in
an aqueous medium, and the above-mentioned (a2) polycarbonate
polyol has a number average molecular weight of 600 to 5000, has
2.05 to 5 hydroxyl groups in average in one molecule, and has an
acidic group; (6) the aqueous polyurethane resin dispersion
described in the above-mentioned (5), wherein (A) the polyurethane
prepolymer is obtained by reacting (a2) the polycarbonate polyol
having no urethane bonding, (a') a polycarbonate diol and (c) a
polyisocyanate, and the above-mentioned (a2) polycarbonate polyol
has a number average molecular weight of 600 to 5000, has 2.05 to 5
hydroxyl groups in average in one molecule, and has an acidic
group; (7) the aqueous polyurethane resin dispersion described in
the above-mentioned (5) or (6), wherein (a2) the polycarbonate
polyol is a material obtained by subjecting a polycarbonate diol
containing an acidic group obtained by reacting a polycarbonate
diol and (b) a polyol compound having an acidic group, and one or
more polyol compounds selected from a triol compound, a tetraol
compound and a pentaol compound to transesterification reaction;
(8) a process for preparing an aqueous polyurethane resin
dispersion which comprises the steps of: Step (.alpha.1) of
reacting (a1) a polycarbonate polyol having no urethane bonding,
(b) a polyol compound having an acidic group and (c) a
polyisocyanate to obtain (A) a polyurethane prepolymer, Step
(.beta.) of neutralizing the acidic group of the above-mentioned
(A) polyurethane prepolymer, Step (.gamma.) of dispersing the
above-mentioned (A) polyurethane prepolymer in an aqueous medium,
and Step (.delta.) of reacting the above-mentioned (A) polyurethane
prepolymer and (B) a chain elongating agent having a reactivity
with the isocyanate group of the above-mentioned (A) polyurethane
prepolymer to obtain an aqueous polyurethane resin, wherein the
above-mentioned (a1) polycarbonate polyol has a number average
molecular weight of 400 to 5000, and has 2.05 to 5 hydroxyl groups
in average in one molecule; (9) the process for preparing an
aqueous polyurethane resin dispersion as described in the
above-mentioned (8), wherein Step (.alpha.1) to obtain (A) the
polyurethane prepolymer is a step of obtaining (A) a polyurethane
prepolymer by reacting (a1) a polycarbonate polyol having no
urethane bonding, (a') a polycarbonate diol, (b) a polyol compound
having an acidic group, and (c) a polyisocyanate, where the
above-mentioned (a1) polycarbonate polyol has a number average
molecular weight of 400 to 5000, and has 2.05 to 5 hydroxyl groups
in average in one molecule; (10) a process for preparing an aqueous
polyurethane resin dispersion which comprises the steps of: Step
(.alpha.2) of reacting (a2) a polycarbonate polyol having no
urethane bonding and (c) a polyisocyanate to obtain (A) a
polyurethane prepolymer, Step (.beta.) of neutralizing an acidic
group of the above-mentioned (A) polyurethane prepolymer, Step
(.gamma.) of dispersing the above-mentioned (A) polyurethane
prepolymer in an aqueous medium, and Step (.delta.) of reacting the
above-mentioned (A) polyurethane prepolymer and (B) a chain
elongating agent having a reactivity with the isocyanate group of
the above-mentioned (A) polyurethane prepolymer to obtain an
aqueous polyurethane resin, wherein the above-mentioned (a2)
polycarbonate polyol has a number average molecular weight of 600
to 5000, has 2.05 to 5 hydroxyl groups in average in one molecule,
and has an acidic group; (12) the process for preparing an aqueous
polyurethane resin dispersion as described in the above-mentioned
(10), wherein Step (.alpha.2) to obtain (A) the polyurethane
prepolymer is a step of reacting (a2) the polycarbonate polyol
having no urethane bonding, (a') the polycarbonate diol, and (c)
the polyisocyanate to obtain (A) a polyurethane prepolymer, where
the above-mentioned (a2) polycarbonate polyol has a number average
molecular weight of 600 to 5000, has 2.05 to 5 hydroxyl groups in
average in one molecule, and has an acidic group; (12) the process
for preparing an aqueous polyurethane resin dispersion as described
in any one of the above-mentioned (8) to (11), wherein Step
(.beta.) and Step (.gamma.) are carried out simultaneously; (13)
the process for preparing an aqueous polyurethane resin dispersion
as described in any one of the above-mentioned (8) to (11), wherein
Step (.gamma.) and Step (.delta.) are carried out simultaneously;
and (14) a coating composition containing the aqueous polyurethane
resin dispersion as described in any one of the above-mentioned (1)
to (7).
Effects of the Invention
[0012] The aqueous polyurethane resin dispersion of the present
invention has good film-forming property and can form a coating
film which is tough and has flexibility. Also, the process for
preparing the aqueous polyurethane resin dispersion of the present
invention gives an aqueous polyurethane resin dispersion which can
form a coating film having strong toughness and flexibility, and
also having solvent resistance and chemical resistance.
BEST MODE TO CARRY OUT THE INVENTION
(a1) Polycarbonate Polyol
[0013] The (a1) polycarbonate polyol which can be used in the
present invention has a number average molecular weight of 400 to
5000. If the above-mentioned molecular weight is less than 400, the
resulting material is inferior in characteristics as a soft
segment, and cracks will likely caused when a coating film is
formed. If the above-mentioned molecular weight exceeds 5000,
reactivity of (a1) the polycarbonate polyol and (c) the isocyanate
compound is lowered, there are problems that preparation process of
the urethane prepolymer takes much time and the reaction does not
proceed sufficiently, or problems that a viscosity of the
polycarbonate polyol becomes high whereby handling thereof becomes
difficult. A preferred number average molecular weight of (a1) the
polycarbonate polyol is 500 to 3500, particularly preferably 600 to
2500, most preferably 700 to 1900 (when no (a') polycarbonate diol
is used) or 900 to 2000 (when (a') the polycarbonate diol is used).
In the present invention, the number average molecular weight is a
number average molecular weight calculated from quantitative values
of the hydroxyl value and .sup.1H-NMR or by gas chromatography
after alkali hydrolysis of the composition.
[0014] The above-mentioned (a1) polycarbonate polyol has 2.05 to 5
hydroxyl groups in average in one molecule. If a number of the
above-mentioned hydroxyl groups is less than 2.05, modulus of
elasticity of a coating film formed by using the obtained aqueous
polyurethane resin dispersion becomes low, and effects in the point
of solvent resistance or chemical resistance become low. If a
number of the above-mentioned hydroxyl group exceeds 5, a density
of cross-linking points in the urethane prepolymer is too high, and
modulus of elasticity of a coating film formed by using the
obtained aqueous polyurethane resin dispersion becomes high whereby
the film likely causes cracks. The (a1) polycarbonate polyol
preferably has 2.1 to 4.9 hydroxyl groups (when no (a')
polycarbonate diol is used) in average or 2.05 to 4.0 hydroxyl
groups (when (a') the polycarbonate diol is used) in average in one
molecule.
[0015] The above-mentioned (a1) polycarbonate polyol has
substantially no urethane bonding. Also, the above-mentioned (a1)
polycarbonate polyol has substantially no acidic group.
[0016] A polyurethane resin dispersion in an aqueous medium
obtained by using a polycarbonate diol and a polyol compound
without using the above-mentioned (a1) polycarbonate polyol,
reacting these with (b) a polyol compound having an acidic group
and (c) a polyisocyanate to prepare a polyurethane prepolymer, and
reacting the polyurethane prepolymer with (B) a chain elongating
agent under the similar conditions, causes a portion in which a
density of urethane bondings is high in the molecule since the
urethane bondings obtained by the reaction of the polyol compound
and the isocyanate compound are accumulated at the portion branched
by the polyol as mentioned above. As compared with the above, the
polyurethane resin dispersion obtained by using the above-mentioned
(a1) polycarbonate polyol difficultly causes the above-mentioned
accumulation of the urethane bondings, so that film formation is
good and a coating film with tough and flexibility can be formed.
Also, a coating film formed by using the polyurethane resin
dispersion obtained by using the above-mentioned (a1) polycarbonate
polyol has strong toughness and flexibility, and has
characteristics of solvent resistance and chemical resistance.
[0017] The above-mentioned (a1) polycarbonate polyol may be any
material so long as it satisfies the above-regulated requirements.
The (a1) polycarbonate polyol may be, for example, a material
obtained by reacting a diol compound, one or more polyol compounds
selected from a triol compound, a tetraol compound and a pentaol
compound, and a carbonate compound, or else, a material obtained by
subjecting a polycarbonate diol obtained by reacting a diol
compound and a carbonate, and one or more polyol compounds selected
from a triol compound, a tetraol compound and a pentaol compound to
transesterification reaction, a material obtained by subjecting a
polycarbonate polyol obtained by reacting one or more polyol
compounds selected from a triol compound, a tetraol compound and a
pentaol compound and a carbonate compound, and a polycarbonate diol
to transesterification reaction, or a material obtained by
subjecting a polycarbonate diol and one or more polyol compounds
selected from a triol compound, a tetraol compound and a pentaol
compound to transesterification reaction. It may be a material
obtained by subjecting a polycarbonate polyol obtained by reacting
one or more polyol compounds selected from a triol compound, a
tetraol compound and a pentaol compound and a carbonate compound,
and a diol compound to transesterification reaction, preferably a
polycarbonate polyol obtained by reacting a diol compound, a polyol
compound and a carbonate compound. As the polyol compound, a triol
compound is particularly preferred.
[0018] The above-mentioned a diol compound is not particularly
limited and there may be mentioned, for example, an aliphatic diol
such as 1,6-hexanediol, 1,5-pentanediol, 2-ethyl-1,6-hexanediol,
1,4-butanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol,
2-methyl-1,8-octanediol, diethylene glycol, triethylene glycol,
tetraethylene glycol, etc.; an alicyclic diol such as
1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol,
1,4-cyclohexanediol, 1,3-cyclopentanediol, 1,4-cycloheptanediol,
2,5-bis(hydroxymethyl)-1,4-dioxane, 2,7-norbornanediol,
tetrahydrofuran dimethanol, 1,4-bis(hydroxyethoxy)cyclohexane,
etc.; and an aromatic diol such as bisphenol A, etc., and of these,
an aliphatic diol is preferred.
[0019] The above-mentioned triol compound is not particularly
limited, and may be mentioned, for example, a trimethylol alkane
such as trimethylolethane or trimethylolpropane, etc., or
3-methylpentane-1,3,5-triol or glycerine, etc. Of these,
trimethylolpropane is preferred since it can be easily
obtained.
[0020] The tetraol compound is not particularly limited, and, for
example, there may be mentioned butanetetraol, pentanetetraol,
hexanetetraol, etc.
[0021] The pentaol compound is not particularly limited, and, for
example, there may be mentioned pentane pentaol, hexane pentaol,
etc.
[0022] The polyol compound selected from a diol compound and a
triol compound, a tetraol compound and a pentaol compound to be
used for the preparation of (a1) the polycarbonate polyol each does
not contain an acidic group.
[0023] When (a') the polycarbonate diol is not used, a ratio of a
molar number of the polyol component (preferably triol component)
to a molar number of the diol component in (a1) the polycarbonate
polyol is preferably 0.01 to 1, more preferably 0.04 to 0.07, and
when (a') the polycarbonate diol is used, a ratio of a molar number
of the polyol component to a molar number of the diol component in
(a1) the polycarbonate polyol is preferably 0.05 to 1, more
preferably 0.1 to 0.5.
[0024] The above-mentioned carbonate is not particularly limited,
and may be mentioned, for example, an aliphatic carbonate such as
dimethylcarbonate, diethyl carbonate, etc., an aromatic carbonate
such as diphenyl carbonate, etc., a cyclic carbonate compound such
as ethylene carbonate, etc. Also, phosgene which can form the
similar polycarbonate polyol can be used. Of these, an aliphatic
carbonate is preferred since the above-mentioned polycarbonate
polyol can be easily prepared, and dimethylcarbonate is
particularly preferred.
[0025] The (a1) polycarbonate polyol can be obtained by reacting a
diol compound, a polyol compound and a carbonate. In this case, a
ratio of a molar number of the above-mentioned polyol compound to a
molar number of the above-mentioned diol compound is preferably
0.01 to 1 when no (a') polycarbonate diol is used, and preferably
0.05 to 1 when (a') the polycarbonate diol is used. If a ratio of
the above-mentioned polyol compound is too little, a number of the
hydroxyl groups in average in (a1) the polycarbonate polyol
molecule tends to be little, and modulus of elasticity of a coating
film formed by using the obtained aqueous polyurethane resin
dispersion tends to be low in some cases. If a ratio of the
above-mentioned polyol compound is too much, a number of the
hydroxyl groups in average in (a1) the polycarbonate polyol
molecule tends to be much, and modulus of elasticity of a coating
film formed by using the obtained aqueous polyurethane resin
dispersion tends to be high so that the film easily causes cracks
in some cases. A ratio of a molar number of the above-mentioned
polyol compound based on a molar number of the above-mentioned a
diol compound is, when no (a') polycarbonate diol is used,
particularly preferably 0.04 to 0.07, and when (a') the
polycarbonate diol is used, particularly preferably 0.1 to 0.5.
[0026] When (a1) the polycarbonate polyol is to be obtained by
reacting the above-mentioned diol compound, the polyol compound and
the carbonate, a ratio of a molar number of the above-mentioned a
carbonate compound based on the total molar number of the
above-mentioned diol compound and the above-mentioned triol
compound is preferably 0.7 to 1.3, more preferably 0.9 to 1.1.
[0027] The (a1) polycarbonate polyol can be obtained by subjecting
a polycarbonate diol and one or more polyol compounds selected from
a triol compound, a tetraol compound and a pentaol compound to
transesterification reaction, and in this case, a molar ratio of
the polycarbonate diol and the polyol compound is preferably 0.01
to 1, particularly preferably 0.01 to 0.7. The polycarbonate diol
can be obtained by reacting the above-mentioned diol compound and
the above-mentioned carbonate compound.
[0028] The (a1) polycarbonate polyol can be obtained by subjecting
the above-mentioned polycarbonate diol, and a polycarbonate polyol
obtained by reacting one or more polyol compounds selected from a
triol compound, a tetraol compound and a pentaol compound and a
carbonate compound to transesterification reaction, and in this
case, a ratio of a molar number of the polyol component based on a
molar number of the diol component in (a1) the polycarbonate polyol
is preferably 0.01 to 1, more preferably 0.01 to 0.7.
[0029] When the above-mentioned (a1) polycarbonate polyol
prepolymer is to be prepared by transesterification reaction, a
catalyst to be used may be mentioned a catalyst
(transesterification catalyst) which is used in a usual
transesterification reaction. The transesterification catalyst may
be mentioned, as a catalyst, for example, an alkali metal compound
such as a hydroxide of an alkali metal (lithium hydroxide, sodium
hydroxide, potassium hydroxide, etc.), a carbonic acid salt of an
alkali metal (lithium carbonate, sodium carbonate, potassium
carbonate, etc.), a carboxylic acid salt of an alkali metal
(lithium acetate, sodium acetate, potassium acetate, etc.), an
alkali metal alkoxide (lithium methoxide, sodium methoxide,
potassium t-butoxide, etc.), etc., an alkaline earth metal compound
such as a hydroxide of an alkaline earth metal (magnesium
hydroxide, etc.), an alkaline earth metal alkoxide (magnesium
methoxide, etc.), etc., an aluminum compound such as aluminum
alkoxide (aluminum ethoxide, aluminum isopropoxide, aluminum
s-butoxide, etc.), aluminum acetylacetonate, etc., a zinc compound
such as a carboxylic acid salt of zinc (zinc acetate, etc.), zinc
acetyl-acetonate, etc., a manganese compound such as a carboxylic
acid salt of manganese (manganese acetate, etc.), manganese
acetylacetonate, etc., a nickel compound such as a carboxylic acid
salt of nickel (nickel acetate, etc.), nickel acetylacetonate,
etc., an antimony compound such as a carboxylic acid salt of
antimony (antimony acetate, etc.), antimony alkoxide, etc., a
zirconium compound such as zirconium alkoxide (zirconium propoxide,
zirconium butoxide, etc.), zirconium acetylacetonate, etc., a
titanium compound such as titanium alkoxide (tetraethoxytitanium,
tetrapropoxytitanium, tetrabutoxytitanium, etc.), etc., and an
organic tin compound (dibutyl tin oxide, dibutyl tin diacetate,
dibutyl tin dilaurate), etc.
(a2) Polycarbonate Polyol
[0030] The (a2) polycarbonate polyol which can be used in the
present invention has an average molecular weight of 600 to 5000.
If the above-mentioned molecular weight is less than 600, it is
inferior in characteristics as a soft segment, and cracks are
easily occurred when a coating film is formed. If the
above-mentioned molecular weight exceeds 5000, reactivity of (a2)
the polycarbonate polyol and (c) the isocyanate compound is
lowered, whereby there are problems that preparation process of the
urethane prepolymer takes much time, or the reaction does not
proceed sufficiently, or problems that a viscosity of the
polycarbonate polyol becomes high whereby handing thereof becomes
difficult, etc. A preferred number average molecular weight of (a2)
the polycarbonate polyol is 700 to 3500 when no (a') polycarbonate
diol is used, particularly preferably 900 to 2000, and when (a')
the polycarbonate diol is used, it is preferably 700 to 3500,
particularly preferably 900 to 3000, and most preferably 1000 to
2000.
[0031] The above-mentioned (a2) polycarbonate polyol has 2.05 to 5
hydroxyl groups in average in one molecule. If a number of the
above-mentioned hydroxyl group is less than 2.05, modulus of
elasticity of a coating film obtained by using the resulting
aqueous polyurethane resin dispersion becomes low. Also, if a
number of the above-mentioned hydroxyl group exceeds 5, a density
of cross-linking points in the urethane prepolymer is too high,
whereby modulus of elasticity of a coating film obtained by using
the resulting aqueous polyurethane resin dispersion becomes high
and the film likely causes cracks. The (a2) polycarbonate polyol
preferably has 2.1 to 4.9 hydroxyl groups in average in one
molecule when no (a') polycarbonate diol is used, and has 2.05 to
4.0 hydroxyl groups in average in the same when (a') the
polycarbonate diol is used.
[0032] The above-mentioned (a2) polycarbonate polyol has an acidic
group(s). The acidic group is not particularly limited, and there
may be mentioned, for example, a carboxyl group, sulfonyl group,
phospholic acid group and phenolic hydroxyl group. Of these, a
carboxyl group is preferred in the points that it can be obtained
easily and handling thereof is easy and simple.
[0033] The above-mentioned (a2) polycarbonate polyol does not
substantially have urethane bonding.
[0034] The polyurethane resin dispersion in an aqueous medium
obtained by using a polycarbonate diol and a polyol compound
without using the above-mentioned (a2) polycarbonate polyol,
reacting these with (b) a polyol compound having an acidic group
and (c) a polyisocyanate to prepare a polyurethane prepolymer, and
by reacting the polyurethane prepolymer with a chain elongating
agent under the similar conditions, causes a portion in which a
density of urethane bondings is high in the molecule since the
urethane bondings obtained by the reaction of the polyol compound
and the isocyanate compound are accumulated at the portion branched
by the polyol as mentioned above. As compared with the above, the
polyurethane resin dispersion obtained by using the above-mentioned
(a2) polycarbonate polyol hardly causes accumulation of the
urethane bonding as mentioned above. Thus, it has a good
film-forming property, and can form a coating film which is tough
and has flexibility. In addition, the coating film formed by using
the polyurethane resin dispersion obtained by using the
above-mentioned (a2) polycarbonate polyol has characteristics that
it has strong toughness and flexibility, and also has solvent
resistance and chemical resistance.
[0035] The above-mentioned (a2) polycarbonate polyol may be any
material so long as it satisfies the requirements regulated as
mentioned above. The (a2) polycarbonate polyol can be obtained by
subjecting a polycarbonate diol containing an acidic group obtained
by reacting a polycarbonate diol and (b) a polyol compound having
an acidic group, and one or more polyol compounds selected from a
triol compound, a tetraol compound and a pentaol compound to
transesterification reaction, or, by reacting a polycarbonate
polyol obtained by reacting a polycarbonate diol, one or more
polyol compounds selected from a triol compound, a tetraol compound
and a pentaol compound and a carbonate compound, with (b) a polyol
compound having an acidic group, by reacting a second polycarbonate
polyol which is obtained by reacting a polycarbonate polyol
obtained by reacting one or more polyol compounds selected from a
triol compound, a tetraol compound and a pentaol compound and a
carbonate compound, with a polycarbonate diol, and (b) a polyol
compound having an acidic group, by reacting a polycarbonate polyol
which is obtained by reacting a diol compound, one or more polyol
compounds selected from a triol compound, a tetraol compound and a
pentaol compound and a carbonate compound, with (b) a polyol
compound having an acidic group, by reacting a second polycarbonate
polyol obtained by reacting a polycarbonate polyol which is
obtained by reacting one or more polyol compounds selected from a
triol compound, a tetraol compound and a pentaol compound, and a
carbonate compound with (b) a polyol compound having an acidic
group, with a diol compound, by reacting a polycarbonate polyol
obtained by reacting a polycarbonate diol and one or more polyol
compounds selected from a triol compound, a tetraol compound and a
pentaol compound, and (b) a polyol compound having an acidic group,
by reacting a second polycarbonate polyol obtained by reacting a
polycarbonate polyol which is obtained by reacting one or more
polyol compounds selected from a triol compound, a tetraol compound
and a pentaol compound, and a carbonate compound with a diol
compound, with (b) a polyol compound having an acidic group,
preferably a material obtained by reacting a second polycarbonate
polyol obtained by reacting a polycarbonate polyol which is
obtained by reacting one or more polyol compounds selected from a
triol compound, a tetraol compound and a pentaol compound, and a
carbonate compound with a polycarbonate diol, with (b) a polyol
compound having an acidic group.
[0036] The polycarbonate diol which is a starting material of the
above-mentioned (a2) polycarbonate polyol, one or more polyol
selected from a triol compound, a tetraol compound and a pentaol
compound, the carbonate compound, and the catalyst, etc., can be
used as those mentioned in the above-mentioned (a1) polycarbonate
polyol.
(a') Polycarbonate Diol
[0037] The above-mentioned (a') polycarbonate diol can be obtained
by reacting a diol compound and a carbonate. The (a') polycarbonate
diol does not substantially contain a urethane bonding and an
acidic group. The diol compound and the carbonate compound can be
used those described in (a1) the polycarbonate polyol. A number
average molecular weight of (a') the polycarbonate diol is
preferably 500 to 5000, particularly preferably 900 to 3000. If the
number average molecular weight of (a') the polycarbonate diol is
too small, a number of the urethane bondings becomes large as a
result, so that dispersibility of the aqueous polyurethane resin
dispersion tends to be worse, while a number average molecular
weight of (a') the polycarbonate diol is too large, strength of the
coating film tends to be lowered.
[0038] In the present invention, (a1) the polycarbonate polyol,
(a2) the polycarbonate polyol and (a') the polycarbonate diol are
polyols different from each other.
(b) Polyol Compound Having an Acidic Group
[0039] The above-mentioned (b) polyol compound having an acidic
group preferably has 2 hydroxyl groups in one molecule, and the
acidic group is not particularly limited, and there may be
mentioned a carboxyl group, sulfonyl group, phospholic acid group
and phenolic hydroxyl group. Of these, a carboxyl group is
preferred in the points that it can be obtained easily and handling
thereof is easy and simple. The (b) polyol compound having an
acidic group which can be used in the present invention may be more
specifically mentioned a dimethylolalkanoic acid such as
2,2-dimethylol propionic acid, 2,2-dimethylolbutanoic acid, etc.;
and N,N-bishydroxyethylglycine, N,N-bishydroxyethylalanine,
3,4-dihydroxybutanesulfonic acid, and
3,6-dihydroxy-2-toluenesulfonic acid, etc. Of these, a
dimethylolalkanoic acid is preferred in the point that it can be
obtained easily, and 2,2-dimethylol propionic acid is more
preferred.
[0040] The (a2) polycarbonate polyol can be obtained by various
reactions of the diol compound, one or more polyol compounds
selected from a triol compound, a tetraol compound and a pentaol
compound, (b) the polyol compound having an acidic group and the
carbonate compound as mentioned above. In this case, a ratio of a
molar number of the above-mentioned polyol compound to a molar
number of the above-mentioned diol compound is preferably 0.01 to
1, particularly preferably 0.01 to 0.7 when no (a') polycarbonate
diol is used, and when (a') the polycarbonate diol is used, it is
preferably 0.05 to 1, particularly preferably 0.1 to 0.5.
[0041] The (a2) polycarbonate polyol can be also obtained by
subjecting the acidic group-containing polycarbonate diol obtained
by reacting the polycarbonate diol and (b) the polyol compound
having an acidic group, and one or more polyol compounds selected
from a triol compound, a tetraol compound and a pentaol compound to
transesterification reaction.
(c) Polyisocyanate Compound
[0042] (c) The polyisocyanate compound which can be used in the
present invention is not particularly limited, and, more
specifically there may be mentioned an aromatic polyisocyanate
compound such as 1,3-phenylenediisocyanate, 1,4-phenylene
diisocyanate, 2,4-tolylene diisocyanate (TDI), 2,6-tolylene
diisocyanate, 4,4'-diphenylenemethane diisocyanate (MDI),
2,4-diphenylmethane diisocyanate, 4,4'-diisocyanat-biphenyl,
3,3'-dimethyl-4,4'-diisocyanat biphenyl,
3,3'-dimethyl-4,4'-diisocyanat diphenylmethane, 1,5-naphthylene
diisocyanate, 4,4',4''-triphenylmethane triisocyanate,
m-isocyanatphenylsulfonyl isocyanate, p-isocyanatphenylsulfonyl
isocyanate, etc.; an aliphatic polyisocyanate compound such as
ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene
diisocyanate (HDI), dodecamethylene diisocyanate, 1,6,11-undecane
triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine
diisocyanate, 2,6-diisocyanatmethyl caproate,
bis(2-isocyanatethyl)fumarate, bis(2-isocyanatethyl) carbonate,
2-isocyanatethyl-2,6-diisocyanathexanoate, etc.; an alicyclic
polycyanate compound such as isophorone diisocyanate (IPDI),
4,4'-dicyclohexyl-methanediisocyanate (hydrogen-added MDI),
cyclohexylenediisocyanate, methylcyclohexylenediisocyanate
(hydrogen added TDI),
bis(2-isocyanateethyl)-4-cyclohexene-1,2-dicarboxylate,
2,5-norbornanediisocyanate, 2,6-norbornanediisocyanate, etc. These
polyisocyanate compounds may be used a single kind alone or two or
more kinds in combination.
[0043] A number of the isocyanate group in the above-mentioned
polyisocyanate compound per one molecule is generally 2, and a
polyisocyanate having 3 or more isocyanate groups such as
triphenylmethanetriisocyanate, etc., may be used in the range in
which the polyurethane resin of the present invention is not
gellated.
[0044] Of the above-mentioned polyisocyanate compounds,
4,4'-diphenylenemethane-diisocyanate (MDI), isophorone diisocyanate
(IPDI), and 4,4'-dicyclohexylmethane-diisocyanate (hydrogen-added
MDI) are preferred in the points of controlling reactivity and
providing high modulus of elasticity.
(A) Polyurethane Prepolymer
[0045] The (A) polyurethane prepolymer which can be used in the
present invention may be a material obtained by reacting the
above-mentioned (a1) polycarbonate polyol, the above-mentioned (b)
polyol compound having an acidic group and the above-mentioned (c)
polyisocyanate compound, or a material obtained by reacting the
above-mentioned (a2) polycarbonate polyol and the above-mentioned
(c) polyisocyanate compound.
[0046] When (A) the urethane prepolymer is to be obtained by
reacting the above-mentioned (a1) polycarbonate polyol, the
above-mentioned (b) polyol compound having an acidic group and (c)
the polyisocyanate compound, a molar ratio of the above-mentioned
(b) polyol having an acidic group to the above-mentioned (a1)
polycarbonate polyol is preferably 0.2 to 5.0. If an amount of the
above-mentioned (b) polyol having an acidic group is too little,
dispersibility of the resulting aqueous polyurethane resin
dispersion in an aqueous medium tends to be poor. Also, if an
amount of the above-mentioned (b) polyol having an acidic group is
too much, hydrolysis resistance of the coating film tends to be
lowered. A molar ratio of the above-mentioned (b) polyol having an
acidic group to the above-mentioned (a1) polycarbonate polyol is
particularly preferably 0.5 to 2.5.
[0047] A ratio of a molar number of the isocyanate group in the
above-mentioned (c) polyisocyanate compound to a molar number of
the hydroxyl groups in the polyol components comprising the
above-mentioned (a1) polycarbonate polyol and the above-mentioned
(b) polyol compound having an acidic group, or the above-mentioned
(a2) polycarbonate polyol is preferably 0.8 to 3.0. If a molar
number of the hydroxyl groups in the above-mentioned polyol
components is too much, a number of molecules which have no
isocyanate group at the end of the molecule becomes large so that a
number of the molecules which do not react with the chain
elongating agent becomes large, whereby there is a problem that
film-forming property of a coating film obtained by coating the
aqueous polyurethane resin dispersion of the present invention is
poor. Also, if a molar number of the hydroxyl groups in the polyol
components is too little, the above-mentioned unreacted (c)
polyisocyanate compound remains in the reaction system with a
larger amount, which sometimes reacts with the above-mentioned
chain elongating agent, or reacts with water to cause molecular
elongation, whereby there is a problem that seeding is generated in
the coating film obtained by coating the aqueous polyurethane resin
dispersion of the present invention. A ratio of a molar number of
the isocyanate group in the above-mentioned (c) polyisocyanate
compound to a molar number of the hydroxyl groups in the polyol
components is particularly preferably 1.0 to 2.5.
[0048] The (A) polyurethane prepolymer which can be used in the
present invention may be a material obtained by reacting the
above-mentioned (a1) polycarbonate polyol, (a') the polycarbonate
diol, the above-mentioned (b) polyol compound having an acidic
group and the above-mentioned (c) polyisocyanate compound, or a
material obtained by reacting the above-mentioned (a2)
polycarbonate polyol, (a') the polycarbonate diol and the
above-mentioned (c) polyisocyanate compound.
[0049] When (A) the urethane prepolymer is to be obtained by
reacting the above-mentioned (a1) polycarbonate polyol, (a') the
polycarbonate diol, the above-mentioned (b) polyol compound having
an acidic group and (c) the polyisocyanate compound, a ratio of
(a') the polycarbonate diol based on the above-mentioned (a1)
polycarbonate polyol is preferably 0.5 to 0.8, more preferably 0.6
to 0.7. If an amount of the above-mentioned (a') polycarbonate diol
is too little, flexibility of the coating film obtained by using
the resulting aqueous polyurethane resin dispersion tends to be
poor, while if it is too much, strength of the coating film
obtained by using the resulting aqueous polyurethane resin
dispersion tends to be low in some cases.
[0050] A molar ratio of the above-mentioned (b) polyol having an
acidic group to a molar number of the sum of the above-mentioned
(a1) polycarbonate polyol and (a') the polycarbonate diol is
preferably 0.2 to 5.0. If an amount of the above-mentioned (b)
polyol having an acidic group is too little, dispersibility of the
resulting aqueous polyurethane resin dispersion in an aqueous
medium tends to be poor. While if an amount of the above-mentioned
(b) polyol having an acidic group is too much, hydrolysis
resistance of the coating film tends to be lowered in some cases. A
molar ratio of the above-mentioned (b) polyol having an acidic
group to a molar number of the sum of the above-mentioned (a1)
polycarbonate polyol and (a') the polycarbonate diol is
particularly preferably 0.5 to 2.5.
[0051] A ratio of a molar number of the isocyanate group in the
above-mentioned (c) polyisocyanate compound based on a molar number
of the hydroxyl groups in the polyol components comprising the
above-mentioned (a1) polycarbonate polyol, the above-mentioned (a')
polycarbonate diol and the above-mentioned (b) polyol compound
having an acidic group, or the above-mentioned (a2) polycarbonate
polyol and (a') the polycarbonate diol is preferably 0.8 to 3.0. If
the molar number of the hydroxyl groups in the above-mentioned
polyol components is too much, an amount of the molecules having no
isocyanate group at the molecular ends tends to be much, and an
amount of the molecules which do not react with the chain
elongating agent tends to be much, whereby there is a problem that
a film-forming property of a coating film obtained by coating the
aqueous polyurethane resin dispersion of the present invention is
poor. Also, if the molar number of the hydroxyl groups in the
polyol components is too little, a large amount of unreacted
above-mentioned (c) polyisocyanate compound remains in the reaction
system, which reacts with the above-mentioned chain elongating
agent, or reacts with water to cause molecular elongation, whereby
there is a problem that seeding occurs in a coating film obtained
by coating the aqueous polyurethane resin dispersion of the present
invention. A ratio of a molar number of the isocyanate group in the
above-mentioned (c) polyisocyanate compound based on a molar number
of the hydroxyl groups in the polyol components is particularly
preferably 1.0 to 2.5.
[0052] When the above-mentioned (a1) polycarbonate polyol, the
above-mentioned (b) polyol compound having an acidic group and the
above-mentioned (c) polyisocyanate compound are to be reacted, or
when the above-mentioned (a2) polycarbonate polyol and the
above-mentioned (c) polyisocyanate compound are to be reacted, or,
when the above-mentioned (a1) polycarbonate polyol, (a') the
polycarbonate diol, the above-mentioned (b) polyol compound having
an acidic group and the above-mentioned (c) polyisocyanate compound
are to be reacted, or when the above-mentioned (a2) polycarbonate
polyol, (a') the polycarbonate diol and the above-mentioned (c)
polyisocyanate compound are to be reacted, a catalyst may be
used.
[0053] The above-mentioned catalyst is not particularly limited,
and there may be mentioned, for example, a salt of a metal and an
organic and inorganic acid such as a tin series catalyst (trimethyl
tin laurate, dibutyl tin dilaurate, etc.) or a lead series catalyst
(lead octylate, etc.), etc., and an organometallic derivative,
amine series catalyst (triethylamine, N-ethylmorpholine,
triethylenediamine, etc.), diazabicycloundecene series catalyst,
etc. Of these, dibutyl tin dilaurate is preferred in view of
reactivity.
[0054] A reaction temperature at the time of reacting the
above-mentioned polycarbonate polyol and the above-mentioned
polyisocyanate is not particularly limited, and 40 to 150.degree.
C. are preferred. If the reaction temperature is too low, there is
a case where the starting material(s) is/are not dissolved, or the
resulting (A) urethane prepolymer has high viscosity whereby
stirring is not carried out sufficiently. If the reaction
temperature is too high, there is a case of causing inconvenience
that side reaction occurs, etc. The reaction temperature is more
preferably 60 to 120.degree. C.
(Chain Elongating Agent)
[0055] The (B) chain elongating agent of the present invention has
reactivity with the isocyanate group of (A) the polyurethane
prepolymer. The chain elongating agent may be mentioned, for
example, a diamine compound such as ethylene diamine,
1,4-tetramethylene diamine, 2-methyl-1,5-pentanediamine,
1,4-butanediamine, 1,6-hexamethylenediamine,
1,4-hexamethylenediamine, 3-amino
methyl-3,5,5-trimethylcyclohexylamine, 1,3-bis(amino
methyl)cyclohexane, xylylene diamine, etc.; an amine compound such
as piperazine, 2,5-dimethylpiperazine, diethylenetriamine,
triethylenetetramine, etc., a diol compound such as ethyleneglycol,
propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.,
polyalkylene glycols represented by polyethyleneglycol, and water,
etc., and of these, a primary diamine compound is preferably
mentioned. These may be used alone, or two or more kinds in
combination.
(Aqueous Polyurethane Resin)
[0056] The aqueous polyurethane resin of the present invention can
be obtained by reacting (A) a polyurethane prepolymer and the
above-mentioned (B) chain elongating agent. A temperature of the
reaction is 0 to 80.degree. C., preferably 0 to 60.degree. C.
[0057] An amount of (B) the chain elongating agent to be added is
preferably an equivalent amount or less of the isocyanate group
which becomes a start point of chain elongation in the resulting
urethane polymer. If (B) the chain elongating agent is added in
excess of the equivalent amount of the isocyanate group, a
molecular weight of the chain-elongated urethane polymer is lowered
and a cohesive force of the coating film at the time of
film-formation is lowered. Addition of (B) the chain elongating
agent may be carried out after dispersing the polyurethane
prepolymer in water or may be during dispersing procedure. Chain
elongation may be carried out with water. In this case, water added
as a dispersing medium also acts as a chain elongating agent.
(Aqueous Medium)
[0058] In the present invention, the polyurethane resin is
dispersed in water. The polyurethane resin is dispersed in an
aqueous medium. The above-mentioned aqueous medium may be mentioned
water, a mixed solvent of water and a hydrophilic organic solvent,
etc.
[0059] The above-mentioned water may be mentioned, for example, tap
water, deionized water, distilled water, ultra pure water, etc. Of
these, deionized water is preferably mentioned in consideration
with easiness in obtaining the material and particles being
unstable due the effect of a salt, etc.
[0060] The above-mentioned hydrophilic organic solvent may be
mentioned a lower monovalent alcohol such as methanol, ethanol,
propanol, etc.; a polyvalent alcohol such as ethyleneglycol,
glycerine, etc.; an aprotic hydrophilic organic solvent such as
N-methylmorpholine, dimethylsulfoxide, dimethylformamide,
N-methylpyrrolidone, etc.
[0061] An amount of the above-mentioned hydrophilic organic solvent
in the above-mentioned aqueous medium is preferably 0 to 20% by
weight.
(Aqueous Polyurethane Resin Dispersion)
[0062] The aqueous polyurethane resin dispersion of the present
invention can be prepared by Step (.alpha.) of obtaining (A) a
polyurethane prepolymer, Step (.beta.) of neutralizing the acidic
group of (A) the polyurethane prepolymer, Step (.gamma.) of
dispersing the polyurethane prepolymer in an aqueous medium, and
Step (.delta.) of reacting the isocyanate group of (A) the
polyurethane prepolymer and (B) a chain elongating agent to obtain
an aqueous polyurethane resin.
[0063] Step (.alpha.) to obtain (A) the polyurethane prepolymer may
be carried out under inert gas atmosphere or under ambient air
atmosphere.
[0064] In Step (.beta.) of neutralizing the acidic group of the
above-mentioned (A) polyurethane prepolymer, the neutralizing agent
which can be used may be mentioned organic amines such as
trimethylamine, triethylamine, triisopropylamine, tributylamine,
triethanolamine, N-methyldiethanolamine, N-phenyldiethanolamine,
dimethylethanolamine, diethylethanolamine, N-methylmorpholine,
pyridine, etc.; inorganic alkalis such as sodium hydroxide,
potassium hydroxide, etc., and ammonia, etc. Of the above-mentioned
materials, preferred are organic amines, more preferably tertiary
amine, and most preferably triethylamine.
[0065] In Step (.gamma.) of dispersing the above-mentioned
polyurethane prepolymer in an aqueous medium, a method for
dispersing the polyurethane prepolymer in an aqueous medium is not
particularly limited, and may be mentioned, for example, a method
in which a urethane prepolymer or a urethane prepolymer solution is
added to an aqueous medium which is stirred by a homomixer or a
homogenizer, etc., or a method in which an aqueous medium is added
to a urethane prepolymer stirred by a homomixer or a homogenizer,
etc.
[0066] In Step (.delta.) in which the above-mentioned (A)
polyurethane prepolymer and (B) a chain elongating agent having a
reactivity with the isocyanate group of the above-mentioned (A)
polyurethane prepolymer are reacted to obtain an aqueous
polyurethane resin, the reaction may be carried out slowly under
cooling, or in some cases, the reaction may be promoted under
heating consitions at 60.degree. C. or lower.
[0067] Step (.beta.) of neutralizing an acidic group of the
above-mentioned (A) polyurethane prepolymer, and Step (.gamma.) of
dispersing the above-mentioned (A) polyurethane prepolymer in an
aqueous medium may be carried out simultaneously, and Step
(.gamma.) of dispersing the above-mentioned (A) polyurethane
prepolymer in an aqueous medium, and Step (.delta.) of reacting
with (B) a chain elongating agent to obtain an aqueous polyurethane
resin may be carried out simultaneously.
[0068] A ratio of the polyurethane resin in the aqueous
polyurethane resin dispersion is 5 to 60% by weight, preferably 20
to 50% by weight.
(Coating Composition)
[0069] The present invention relates to a coating composition
containing the above-mentioned aqueous polyurethane resin
dispersion. In a paint of the present invention, it contains the
above-mentioned aqueous polyurethane resin dispersion preferably in
an amount of 5 to 60% by weight, more preferably 10 to 40% by
weight.
[0070] The coating composition of the present invention may contain
other resin(s) than the above-mentioned aqueous polyurethane resin
dispersion. The above-mentioned other resin(s) may be mentioned a
polyester resin, acrylic resin, polyether resin, poly carbonate
resin, polyurethane resin, epoxy resin, alkyd resin, etc. These may
be used alone, or two or more kinds in combination. The
above-mentioned other resin(s) is/are preferably at least one kind
selected from the group consisting of a polyester resin and an
acrylic resin.
[0071] Also, the above-mentioned other resin(s) preferably has one
or more hydrophilic group(s). The above-mentioned hydrophilic
group(s) may be mentioned a hydroxyl group, carboxyl group,
sulfonic acid group, etc.
[0072] When the above-mentioned polyester resin or the
above-mentioned acrylic resin has a hydroxyl group, it may be the
so-called resin urethane-modified polyester resin or
urethane-modified acrylic resin in which these resins are elongated
to be a high molecular weighted by subjecting a part or whole of
the hydroxyl groups and a polyisocyanate compound to urethanization
reaction.
[0073] The above-mentioned polyester resin can be generally
prepared by an esterification reaction or transesterification
reaction of an acid component and an alcohol component.
[0074] The above-mentioned acid component may be used a compound
generally used as an acid component at the time of preparation of
the polyester resin. The acid component may be used, for example,
an aliphatic polybasic acid, alicyclic polybasic acid, aromatic
polybasic acid, etc.
[0075] A hydroxyl value of the above-mentioned polyester resin is
preferably 10 to 300 mg KOH/g or so, more preferably 50 to 250 mg
KOH/g or so, and further preferably 80 to 180 mg KOH/g or so. An
acid value of the above-mentioned polyester resin is preferably 1
to 200 mg KOH/g or so, more preferably 15 to 100 mg KOH/g or so,
and further preferably 25 to 60 mg KOH/g or so. A weight average
molecular weight of the above-mentioned polyester resin is
preferably 500 to 50,000, more preferably 1,000 to 30,000, and
further preferably 1,500 to 20,000.
[0076] The above-mentioned acrylic resin is preferably a hydroxyl
group-containing acrylic resin. The above-mentioned hydroxyl
group-containing acrylic resin can be prepared by copolymerizing a
hydroxyl group-containing polymerizable unsaturated monomer, and,
if necessary, other polymerizable unsaturated monomer(s) which is
copolymerizable with said hydroxyl group-containing polymerizable
unsaturated monomer, for example, by a known method such as a
solution polymerization method in an organic solvent, an emulsion
polymerization method in water, etc.
[0077] The above-mentioned hydroxyl group-containing polymerizable
unsaturated monomer is a compound having a hydroxyl group and a
polymerizable unsaturated bond each one or more in one molecule.
There may be mentioned, for example, a monoesterified product of a
(meth)acrylic acid such as 2-hydroxyethyl(meth)acrylate,
2-hydroxypropyl(meth)acrylate, 3-hydroxypropyl(meth)acrylate,
4-hydroxybutyl(meth)acrylate, etc., and a divalent alcohol having 2
to 8 carbon atoms; an .epsilon.-caprolactone-modified product of
these monoesterified products; N-hydroxymethyl(meta)acrylamide;
allyl alcohol; a (meth)acrylate having a polyoxyethylene chain a
molecular end(s) of which is/are a hydroxyl group(s), etc.
[0078] The above-mentioned hydroxyl group-containing acrylic resin
preferably has a cationic functional group. The hydroxyl
group-containing acrylic resin having a cationic functional group
can be prepared by, for example, using a polymerizable unsaturated
monomer having a cationic functional group such as a tertiary amino
group, quaternary ammonium salt group, etc., as a kind of the
above-mentioned polymerizable unsaturated monomer.
[0079] A hydroxyl value of the above-mentioned hydroxyl
group-containing acrylic resin is preferably 1 to 200 mg KOH/g or
so in view of storage stability or water resistance of the
resulting coating film, etc., more preferably 2 to 100 mg KOH/g or
so, and further preferably 3 to 60 mg KOH/g or so. Also, when the
hydroxyl group-containing acrylic resin has an acidic group such as
a carboxyl group, etc., an acid value of said hydroxyl
group-containing acrylic resin is preferably 1 to 200 mg KOH/g or
so in view of water resistance, etc., of the resulting coating
film, more preferably 2 to 150 mg KOH/g or so, and further
preferably 5 to 100 mg KOH/g or so. A weight average molecular
weight of the above-mentioned hydroxyl group-containing acrylic
resin is preferably 1,000 to 200,000, more preferably 2,000 to
100,000, and further preferably it is suitable in the range of
3,000 to 50,000.
[0080] The above-mentioned polyether resin may be mentioned a
polymer or copolymer having an ether bond, and there may be
mentioned, for example, a polyoxyethylene series polyether, a
polyoxypropylene series polyether, a polyoxybutylene series
polyether, a polyether derived from an aromatic polyhydroxy
compound such as bisphenol A, bisphenol F, etc.
[0081] As the above-mentioned polycarbonate resin, there may be
mentioned a polymer prepared by a bisphenol compound, and, for
example, bisphenol A.cndot.polycarbonate, etc., may be
mentioned.
[0082] The above-mentioned poly carbonate resin may be mentioned a
polymer prepared from a bisphenol compound, and for example,
bisphenol A.cndot.polycarbonate, etc., may be mentioned.
[0083] The above-mentioned polyurethane resin may be mentioned a
resin having an urethane bond which is obtained by the reaction of
various kinds of polyol components such as acrylic, polyester,
polyether, polycarbonate, etc., and a polyisocyanate compound.
[0084] The above-mentioned epoxy resin may be mentioned a resin
obtained by the reaction of a bisphenol compound and
epichlorohydrin, etc. The bisphenol may be mentioned, for example,
bisphenol A, bisphenol F.
[0085] The above-mentioned alkyd resin may be mentioned an alkyd
resin obtained by reacting a polybasic acid such as phthalic acid,
terephthalic acid, succinic acid, etc., and a polyvalent alcohol,
and further with a modifying agent such as oil and fats, oil and
fats aliphatic acid (soybean oil, linseed oil, palm oil, stearic
acid, etc.), a natural resin (rosin, amber, etc.), etc.
[0086] A curing agent may be added to the coating composition of
the present invention, whereby water resistance, etc., of the
coating film or plural-layered coating film prepared by using the
above-mentioned coating composition can be improved. The
above-mentioned curing agent may be used, for example, an amino
resin, polyisocyanate compound, blocked polyisocyanate compound,
melamine resin, carbodiimide, etc. The above-mentioned curing agent
may be used one kind alone, or may be used a plural number thereof
in combination.
[0087] The above-mentioned amino resin may be mentioned, for
example, a partially or completely methylolated amino resin
obtained by the reaction of an amino component and an aldehyde
component. The above-mentioned amino component may be mentioned,
for example, melamine, urea, benzoguanamine, acetoguanamine,
steroguanamine, spiroguanamine, dicyane diamide, etc. The aldehyde
component may be mentioned, for example, formaldehyde,
paraformaldehyde, acetaldehyde, benzaldehyde, etc.
[0088] The above-mentioned polyisocyanate compound may be
mentioned, for example, a compound having 2 or more isocyanate
groups in one molecule, and there may be exemplified by, for
example, hexamethylene diisocyanate, trimethyl hexamethylene
diisocyanate, etc.
[0089] The above-mentioned blocked polyisocyanate compound may be
mentioned those obtained by adding a blocking agent to the
polyisocyanate group of the above-mentioned polyisocyanate
compound, and the blocking agent may be mentioned a blocking agent
including a phenol series material such as phenol, cresol, etc.,
and an aliphatic alcohol series material such as methanol, ethanol,
etc.
[0090] The above-mentioned melamine resin may be mentioned, for
example, methylolmelamine such as dimethylolmelamine,
trimethylolmelamine etc.; an alkyl etherified product or condensate
of these methylolmelamines; a condensate of the alkyl etherified
product of the methylolmelamine, etc.
[0091] To the coating composition of the present invention, a
colored pigment, an extender pigment, or a photoluminescent pigment
may be added.
[0092] The above-mentioned colored pigment may be mentioned, for
example, titanium oxide, zinc white, carbon black, molybdenum red,
Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment,
quinacridone pigment, isoindoline pigment, styrene series pigment,
perylene pigment, etc. They may be used singly or two more kinds in
combination. In particular, it is preferred to use titanium oxide
and/or carbon black as a colored pigment.
[0093] The above-mentioned extender pigment may be mentioned, for
example, clay, kaolin, barium sulfate, barium carbonate, calcium
carbonate, talc, silica, alumina white, etc. They may be used
singly or two more kinds in combination. In particular, it is
preferred to use barium sulfate and/or talc as an extender pigment,
and it is more preferred to use barium sulfate.
[0094] The above-mentioned photoluminescent pigment may be used,
for example, aluminum, copper, zinc, brass, nickel, aluminum oxide,
mica, aluminum oxide coated by titanium oxide or iron oxide, mica
coated by titanium oxide or iron oxide, etc.
[0095] In the coating composition of the present invention, a usual
additive for paint such as a thickening agent, curing catalyst, UV
absorber, photostabilizer, defoaming agent, plasticizer, surface
adjuster, anti-sediment agent, etc., may be contained singly or in
combination of two or more kinds, if necessary.
[0096] A preparation method of the coating composition of the
present invention is not particularly limited, and a conventionally
known preparation method may be employed. In general, the coating
composition can be prepared by mixing the above-mentioned aqueous
polyurethane resin dispersion with the above-mentioned various
kinds of additives, adding an aqueous medium, and regulating a
viscosity suitable for the coating method.
[0097] As a material to be coated by the coating composition, a
metal, plastic, inorganic material, etc., may be mentioned.
[0098] A coating method of the coating composition may be mentioned
a bell coating, spray coating, roll coating, shower coating, dip
coating, etc.
EXAMPLES
[0099] All parts in Examples mean part by weight.
Example 1
Preparation of Polycarbonate Polyol (a1-1)
[0100] In 500 ml of a round-bottom flask made of a glass and
equipped with a fractionating column, a stirrer, a thermometer and
a nitrogen-introducing tube were charged 91.2 parts of
dimethylcarbonate (available from UBE INDUSTRIES, LTD.), 134.2
parts of trimethylolpropane (available from MITSUBISHI GAS CHEMICAL
COMPANY INC.), and 0.1 part of potassium carbonate, and
transesterification reaction was carried out for 3 hours under
normal pressure and under stirring while removing a mixture of
methanol and dimethylcarbonate by distillation. During the
procedure, the reaction temperature was gradually raised from
85.degree. C. to 110.degree. C., and a composition of the
distillate was controlled so that it became an azeotropic
composition of methanol and dimethylcarbonate or a neighbor
thereof. Thereafter, the pressure was gradually reduced to 30 mmHg,
and transesterification reaction was further carried out at
120.degree. C. for 2 hours under stirring while removing a mixture
of methanol and dimethylcarbonate. After completion of the reaction
(after completion of distillation of methanol and
dimethylcarbonate), the reaction mixture was cooled to room
temperature to obtain a polycarbonate polyol prepolymer.
Incidentally, the transesterification reaction was carried out in a
nitrogen stream. The resulting polycarbonate polyol prepolymer had
a number average molecular weight of 500. Next, in 1000 ml of a
round-bottom flask made of a glass and equipped with a stirrer, a
thermometer, a nitrogen-introducing tube and a condenser were
charged 15.0 parts of the obtained polycarbonate polyol prepolymer
and 200 parts of polycarbonate diol (available from UBE INDUSTRIES,
LTD., Trade name: ETERNACOLL UH-200, which uses 1,6-hexanediol and
a carbonate as starting materials, a number average molecular
weight: 2000, hydroxyl value: 56.1 mg KOH/g), and the mixture was
stirred under reduced pressure of 50 mmHg and after reaching to the
reaction temperature to 125.degree. C., the reaction was carried
out at 125.degree. C. for 4 hours. Sampling was carried out in the
course of the reaction, and it was confirmed that the
transesterification reaction reached to equilibrium by GPC
measurement. After completion of the reaction, the reaction mixture
was cooled to room temperature, and dissolved in 540 parts of ethyl
acetate. 100 parts of water was added to the mixture and after
stirring the mixture for 30 minutes, the aqueous layer was removed
by separating the liquids. This operation was carried out once more
to obtain an ethyl acetate solution. To the ethyl acetate solution
was added 50 g of magnesium sulfate and the mixture was stirred for
30 minutes. Then, the mixture was filtered to remove magnesium
sulfate, and ethyl acetate was then removed by distillation to
obtain a trimethylolpropane-containing Polycarbonate polyol (a1-1).
The obtained Polycarbonate polyol (a1-1) had a number average
molecular weight of 1650, and an average hydroxyl group number of
2.8.
(Preparation of Aqueous Polyurethane Resin Dispersion)
[0101] In a reaction device equipped with a stirrer and a heater
were charged 48.0 parts of the above-mentioned
trimethylolpropane-containing polycarbonate polyol (average
molecular weight 1650, an average hydroxyl group number: 2.8), 3.9
parts of dimethylol propionic acid (available from NIPPON KASEI
CHEMICAL CO., LTD.) and 26.1 parts of methylethyl ketone
(hereinafter sometimes referred to as "MEK".) while introducing a
nitrogen gas. Thereafter, the mixture was heated to 60.degree. C.,
and dissolution of dimethylol propionic acid was confirmed. To the
mixture were added 28.6 parts of 4,4-dicyclohexylmethane
diisocyanate (available from SUMITOMO BAYER URETHANE CO., LTD.,
hereinafter sometimes referred to as "hydrogen-added MDI".), and
0.02 part of dibutyl tin dilaurate as a catalyst, and the mixture
was heated to 80.degree. C. to carry out urethanization reaction
over 4 hours. To the mixture was further added 117.0 parts of MEK,
and the resulting mixture was heated to 90.degree. C. for 3 hours
to prepare a prepolymer (Step .alpha.). An NCO group content at the
time of completion of the urethanization reaction was 2.3 wt %.
After cooling the reaction mixture to 30.degree. C., 2.9 parts of
triethylamine was added and mixed to carry out neutralization (Step
.beta.). Further, 187.8 parts of water was added to disperse the
mixture (Step .gamma.). Then, 14.0 parts of a 40 wt % aqueous
hexamethylenediamine solution was added to the mixture, and
chain-elongation reaction was carried out at room temperature for
24 hours (Step .delta.). The aimed product was heated under reduced
pressure from the room temperature to 50.degree. C. for 3 hours to
remove MEK to obtain Polyurethane resin dispersion 1.
Example 2
Preparation of Polycarbonate Polyol (a1-2)
[0102] In a round-bottom flask made of a glass and equipped with a
fractionating column, a stirrer, a thermometer and a
nitrogen-introducing tube were charged 486.4 parts of
dimethylcarbonate, 5.4 parts of trimethylolpropane, 468.0 parts of
1,6-hexanediol and 0.6 part of potassium carbonate, under normal
pressure and under stirring, while removing a mixture of methanol
and dimethylcarbonate by distillation, transesterification reaction
was carried out for 3 hours. During the procedure, the reaction
temperature was gradually raised from 85.degree. C. to 110.degree.
C., and a composition of the distillate was controlled so that it
became an azeotropic composition of methanol and dimethylcarbonate
or a neighbor thereof. Thereafter, the pressure was gradually
reduced to 30 mm Hg, and transesterification reaction was further
carried out at 120.degree. C. for 2 hours under stirring while
removing a mixture of methanol and dimethylcarbonate by
distillation. Sampling was carried out in the course of the
reaction, and it was confirmed that the transesterification
reaction reached to equilibrium by GPC measurement. After
completion of the reaction, the reaction mixture was cooled to room
temperature and dissolved in ethyl acetate. Water was added to the
mixture, the mixture was stirred and the aqueous layer was removed
by separating the liquids. This operation was carried out once more
to obtain an ethyl acetate solution. To the ethyl acetate solutions
was added magnesium sulfate, and the mixture was stirred and then
filtered to remove magnesium sulfate. Thereafter, ethyl acetate was
removed by distillation to obtain Polycarbonate polyol (a1-2). The
resulting Polycarbonate polyol (a1-2) had a number average
molecular weight of 700, and an average hydroxyl group number in
one molecule of 2.1.
(Preparation of Aqueous Polyurethane Resin Dispersion)
[0103] In a reaction device equipped with a stirrer and a heater
were charged 20.3 parts of the above-mentioned Polycarbonate polyol
(a1-2), 3.9 parts of dimethylol propionic acid and 17.6 parts of
MEK while introducing nitrogen. Thereafter, the mixture was heated
to 60.degree. C., and dissolution of dimethylol propionic acid was
confirmed. To the mixture were added hydrogen added 28.6 parts of
MDI and 0.02 part of dibutyl tin dilaurate as a catalyst, and the
mixture was heated to 80.degree. C. to carry out urethanization
reaction over 4 hours. To the mixture was further added 76.3 parts
of MEK, and the resulting mixture was heated to 90.degree. C. for 3
hours to prepare a prepolymer (Step .alpha.). An NCO group content
at the time of completion of the urethanization reaction was 2.9 wt
%. After cooling the reaction mixture to 30.degree. C., 2.9 parts
of triethylamine was added and mixed to carry out neutralization
(Step .beta.). Further, 123.2 parts of water was added to disperse
the mixture (Step .gamma.). Then, 14.8 parts of a 40 wt % aqueous
hexamethylenediamine solution was added to the mixture, and
chain-elongation reaction was carried out at room temperature for
24 hours (Step .delta.). The formed product was heated under
reduced pressure from the room temperature to 50.degree. C. for 3
hours to remove MEK to obtain Aqueous polyurethane resin dispersion
2.
Example 3
Preparation of Polycarbonate Polyol (a1-3)
[0104] In a round-bottom flask made of a glass and equipped with a
fractionating column, a stirrer, a thermometer and a
nitrogen-introducing tube were charged 91.2 parts of
dimethylcarbonate, 134.2 parts of trimethylolpropane and 0.1 part
of potassium carbonate, and transesterification reaction was
carried out for 3 hours under normal pressure and under stirring
while removing a mixture of methanol and dimethylcarbonate by
distillation. During the procedure, the reaction temperature was
gradually raised from 85.degree. C. to 110.degree. C., and a
composition of the distillate was controlled so that it became an
azeotropic composition of methanol and dimethylcarbonate or a
neighbor thereof. Thereafter, the pressure was gradually reduced to
30 mmHg, and transesterification reaction was further carried out
at 120.degree. C. for 2 hours under stirring while removing a
mixture of methanol and dimethylcarbonate by distillation. After
completion of the reaction (after completion of distillation of
methanol and dimethylcarbonate), the reaction mixture was cooled to
room temperature to obtain a polycarbonate polyol prepolymer. The
resulting polycarbonate polyol prepolymer had a number average
molecular weight of 500. Next, in 1000 ml of a round-bottom flask
made of a glass and equipped with a stirrer, a thermometer, a
nitrogen-introducing tube and a condenser were charged 25.0 parts
of the resulting polycarbonate polyol prepolymer and 100 parts of a
polycarbonate diol (available from UBE INDUSTRIES, LTD., Trade
name: "ETERNACOLL UH-100", which uses 1,6-hexanediol and a
carbonate as starting materials, a number average molecular weight:
1000, hydroxyl value: 112.2 mg KOH/g), and the mixture was stirred
under reduced pressure of 50 mmHg and after reaching to the
reaction temperature to 125.degree. C., the reaction was carried
out at 125.degree. C. for 4 hours. Sampling was carried out in the
course of the reaction, and it was confirmed that the
transesterification reaction reached to equilibrium by GPC
measurement. After completion of the reaction, the reaction mixture
was cooled to room temperature and dissolved in ethyl acetate.
Water was added to the mixture, the mixture was stirred and the
aqueous layer was removed by separating the liquids. This operation
was carried out once more to obtain an ethyl acetate solution. To
the ethyl acetate solutions was added magnesium sulfate, and the
mixture was stirred and then filtered to remove magnesium sulfate.
Thereafter, ethyl acetate was removed by distillation to obtain
Polycarbonate polyol (a1-3). The resulting Polycarbonate polyol
(a1-3) had a number average molecular weight of 830, and an average
hydroxyl group number in one molecule of 2.1.
(Preparation of Aqueous Polyurethane Resin Dispersion)
[0105] In a reaction device equipped with a stirrer and a heater
were charged 24.1 parts of the above-mentioned polycarbonate polyol
(a1-3), 3.9 parts of dimethylol propionic acid and 18.9 parts of
MEK while introducing nitrogen. Thereafter, the mixture was heated
to 60.degree. C., and dissolution of dimethylol propionic acid was
confirmed. To the mixture were added 28.6 parts of hydrogen-added
MDI and 0.02 part of dibutyl tin dilaurate as a catalyst, and the
mixture was heated to 80.degree. C. to carry out urethanization
reaction over 4 hours. To the mixture was further added 86.2 parts
of MEK, and the resulting mixture was heated to 90.degree. C. for 3
hours to prepare a prepolymer (Step .alpha.). An NCO group content
at the time of completion of the urethanization reaction was 2.7 wt
%. After cooling the reaction mixture to 30.degree. C., 2.9 parts
of triethylamine and 132.1 parts of water were simultaneously added
and mixed to the mixture to carry out neutralization of Step (Step
.beta.), and dispersing in water of Step (Step .gamma.),
simultaneously. Then, 14.8 parts of a 40 wt % aqueous
hexamethylenediamine solution was added to the mixture, and
chain-elongation reaction was carried out at room temperature for
24 hours (Step .delta.). The formed product was heated under
reduced pressure from the room temperature to 50.degree. C. for 3
hours to remove MEK to obtain Aqueous polyurethane resin dispersion
3.
Example 4
Preparation of Polycarbonate Polyol (a1-4)
[0106] In a round-bottom flask made of a glass and equipped with a
fractionating column, a stirrer, a thermometer and a
nitrogen-introducing tube were charged 84.0 parts of
dimethylcarbonate, 136.2 parts of pentaerythritol and 0.1 part of
potassium carbonate, and transesterification reaction was carried
out for 1 hour under normal pressure and under stirring, while
removing a mixture of methanol and dimethylcarbonate by
distillation. During the procedure, the reaction temperature was
gradually raised from 85.degree. C. to 110.degree. C., and a
composition of the distillate was controlled so that it became an
azeotropic composition of methanol and dimethylcarbonate or a
neighbor thereof. Thereafter, the pressure was gradually reduced to
30 mmHg, and transesterification reaction was further carried out
at 120.degree. C. for 1 hour under stirring while removing a
mixture of methanol and dimethylcarbonate by distillation. After
completion of the reaction (after completion of distillation of
methanol and dimethylcarbonate), the reaction mixture was cooled to
room temperature to obtain a polycarbonate polyol prepolymer. The
resulting polycarbonate polyol prepolymer had a number average
molecular weight of 500. Next, in 1000 ml of a round-bottom flask
made of a glass and equipped with a stirrer, a thermometer, a
nitrogen-introducing tube and a condenser were charged 25.0 parts
of the resulting polycarbonate polyol prepolymer and 200 parts of a
polycarbonate diol (available from UBE INDUSTRIES, LTD., Trade
name: "ETERNACOLL UH-200", molecular weight 2000, hydroxyl value:
56.1 mg KOH/g), and the mixture was stirred under reduced pressure
of 50 mmHg and after reaching to the reaction temperature to
125.degree. C., the reaction was carried out at 125.degree. C. for
4 hours. Sampling was carried out in the course of the reaction,
and it was confirmed that the transesterification reaction reached
to equilibrium by GPC measurement. After completion of the
reaction, the reaction mixture was cooled to room temperature and
dissolved in ethyl acetate. Water was added to the mixture, the
mixture was stirred and the aqueous layer was removed by separating
the liquids. This operation was carried out once more to obtain an
ethyl acetate solution. To the ethyl acetate solutions was added
magnesium sulfate, and the mixture was stirred and then filtered to
remove magnesium sulfate. Thereafter, ethyl acetate was removed by
distillation to obtain Polycarbonate polyol (a1-4). The resulting
Polycarbonate polyol (a1-4) had a number average molecular weight
of 1500, and an average hydroxyl group number in one molecule of
4.2.
(Preparation of Aqueous Polyurethane Resin Dispersion)
[0107] In a reaction device equipped with a stirrer and a heater
were charged 43.5 parts of the above-mentioned Polycarbonate polyol
(a1-4), 3.9 parts of dimethylol propionic acid and 25.3 parts of
MEK while introducing nitrogen. Thereafter, the mixture was heated
to 60.degree. C., and dissolution of dimethylol propionic acid was
confirmed. To the mixture were added 28.6 parts of hydrogen-added
MDI and 0.02 part of dibutyl tin dilaurate as a catalyst, and the
mixture was heated to 80.degree. C. to carry out urethanization
reaction over 4 hours. To the mixture was further added 109.8 parts
of MEK, and the resulting mixture was heated to 90.degree. C. for 3
hours to prepare a prepolymer (Step .alpha.). An NCO group content
at the time of completion of the urethanization reaction was 2.0 wt
%. After cooling the reaction mixture to 30.degree. C., 2.9 parts
of triethylamine was added and mixed to carry out neutralization
(Step .beta.). Further, 136.8 parts of water was added to disperse
the mixture (Step .gamma.). Then, 14.8 parts of a 40 wt % aqueous
hexamethylenediamine solution was added to the mixture, and
chain-elongation reaction was carried out at room temperature for
24 hours (Step 6). The formed product was heated under reduced
pressure from the room temperature to 50.degree. C. for 3 hours to
remove MEK to obtain Aqueous polyurethane resin dispersion 4.
Example 5
Preparation of Polycarbonate Polyol (a1-5)
[0108] In a round-bottom flask made of a glass and equipped with a
fractionating column, a stirrer, a thermometer and a
nitrogen-introducing tube were charged 84.0 parts of
dimethylcarbonate, 136.2 parts of pentaerythritol and 0.1 part of
potassium carbonate, and transesterification reaction was carried
out for 1 hour under normal pressure and under stirring, while
removing a mixture of methanol and dimethylcarbonate by
distillation. During the procedure, the reaction temperature was
gradually raised from 85.degree. C. to 110.degree. C., and a
composition of the distillate was controlled so that it became an
azeotropic composition of methanol and dimethylcarbonate or a
neighbor thereof. Thereafter, the pressure was gradually reduced to
30 mmHg, and transesterification reaction was further carried out
at 120.degree. C. for 1 hour under stirring while removing a
mixture of methanol and dimethylcarbonate by distillation. After
completion of the reaction (after completion of distillation of
methanol and dimethylcarbonate), the reaction mixture was cooled to
room temperature to obtain a polycarbonate polyol prepolymer. The
resulting polycarbonate polyol prepolymer had a number average
molecular weight of 500. Next, in 1000 ml of a round-bottom flask
made of a glass and equipped with a stirrer, a thermometer, a
nitrogen-introducing tube and a condenser were charged 40.0 parts
of the resulting polycarbonate polyol prepolymer and 300 parts of a
polycarbonate diol (available from UBE INDUSTRIES, LTD., Trade
name. "ETERNACOLL UH-300", which uses 1,6-hexanediol and a
carbonate as starting materials, a number average molecular weight
3000, hydroxyl value: 37.4 mg KOH/g), and the mixture was stirred
under reduced pressure of 50 mmHg and after reaching to the
reaction temperature to 125.degree. C., the reaction was carried
out at 125.degree. C. for 4 hours. Sampling was carried out in the
course of the reaction, and it was confirmed that the
transesterification reaction reached to equilibrium by GPC
measurement. After completion of the reaction, the reaction mixture
was cooled to room temperature and dissolved in ethyl acetate.
Water was added to the mixture, the mixture was stirred and the
aqueous layer was removed by separating the liquids. This operation
was carried out once more to obtain an ethyl acetate solution. To
the ethyl acetate solutions was added magnesium sulfate, and the
mixture was stirred and then filtered to remove magnesium sulfate.
Thereafter, ethyl acetate was removed by distillation to obtain
Polycarbonate polyol (a1-5). The resulting Polycarbonate polyol
(a1-5) had a number average molecular weight of 1900, and an
average hydroxyl group number in one molecule of 4.9.
(Preparation of Aqueous Polyurethane Resin Dispersion)
[0109] In a reaction device equipped with a stirrer and a heater
were charged 55.1 parts of the above-mentioned Polycarbonate polyol
(a1-5), 3.9 parts of dimethylol propionic acid and 29.2 parts of
MEK while introducing nitrogen. Thereafter, the mixture was heated
to 60.degree. C., and dissolution of dimethylol propionic acid was
confirmed. To the mixture were added 28.6 parts of hydrogen-added
MDI and 0.02 part of dibutyl tin dilaurate as a catalyst, and the
mixture was heated to 80.degree. C. to carry out urethanization
reaction over 4 hours. To the mixture was further added 126.5 parts
of MEK, and the resulting mixture was heated to 90.degree. C. for 3
hours to prepare a prepolymer (Step .alpha.). An NCO group content
at the time of completion of the urethanization reaction was 1.8 wt
%. After cooling the reaction mixture to 30.degree. C., 2.9 parts
of triethylamine was added and mixed to carry out neutralization
(Step .beta.). Further, 204.4 parts of water and 14.8 parts of a 40
wt % aqueous hexamethylenediamine solution were simultaneously
added to the mixture, and chain-elongation reaction was carried out
at room temperature for 24 hours (Step .gamma., Step .delta.). The
formed product was heated under reduced pressure from the room
temperature to 50.degree. C. for 3 hours to remove MEK to obtain
Aqueous polyurethane resin dispersion 5.
Example 6
Preparation of (a2) Polycarbonate Polyol
[0110] In the same manner as in Example 1, Polycarbonate polyol
(a1-1) having a number average molecular weight of 1650 and an
average hydroxyl group number of 2.8 was synthesized. In a reaction
device equipped with a stirrer and a heater were charged 165 parts
of Polycarbonate polyol (a1-1) and 13.4 parts of dimethylol
propionic acid, and the mixture was heated to 160.degree. C. To the
mixture was charged 0.05 part of tetrabutyl titanate, and the
mixture was reacted at 180.degree. C. for 6 hours to obtain a
carboxylic acid-containing polycarbonate polyol. The resulting
Polycarbonate polyol (a2) had a number average molecular weight of
890, and an average hydroxyl group number in one molecule of
2.4.
(Preparation of Aqueous Polyurethane Resin Dispersion)
[0111] In a reaction device equipped with a stirrer and a heater
were charged 44.5 parts of the above-mentioned Polycarbonate polyol
(a2) and 26.1 parts of MEK while introducing nitrogen. To the
mixture were added 23.0 parts of hydrogen-added MDI and 0.02 part
of dibutyl tin dilaurate as a catalyst, and the mixture was heated
to 80.degree. C. to carry out urethanization reaction over 4 hours.
To the mixture was further added 117.0 parts of MEK, and the
resulting mixture was heated to 90.degree. C. for 3 hours to
prepare a prepolymer (Step .alpha.). An NCO group content at the
time of completion of the urethanization reaction was 1.5 wt %.
After cooling the reaction mixture to 30.degree. C., 2.5 parts of
triethylamine was added and mixed to carry out neutralization (Step
.beta.). Further, 157.6 parts of water was added to disperse the
mixture (Step .gamma.). Then, 10.4 parts of a 40 wt % aqueous
hexamethylenediamine solution was added to the mixture, and
chain-elongation reaction was carried out (Step .delta.). The
product was heated under reduced pressure at 50.degree. C. for 3
hours to remove MEK to obtain Aqueous polyurethane resin dispersion
6.
Comparative Example 1
[0112] In a reaction device equipped with a stirrer and a heater
were charged 59.1 parts of "ETERNACOLL UH-200" (available from UBE
INDUSTRIES, LTD., a polycarbonate diol using 1,6-hexanediol and
dimethylcarbonate as starting materials and having a number average
molecular weight of 2000, an average hydroxyl group number: 2)
having a hydroxyl value of 56.1, 1.0 part of trimethylolpropane,
5.0 parts of dimethylol propionic acid and 41.0 parts of MEK while
introducing nitrogen. Thereafter, the mixture was heated to
60.degree. C., and dissolution of dimethylol propionic acid was
confirmed. To the mixture were added 30.5 parts of hydrogen-added
MDI and 0.04 part of dibutyl tin dilaurate as a catalyst, and the
mixture was heated to 80.degree. C. to carry out urethanization
reaction over 4 hours to prepare a prepolymer. An NCO group content
at the time of completion of the urethanization reaction was 4.7 wt
%. After cooling the reaction mixture to 30.degree. C., 53.9 parts
of MEK was additionally added to the mixture, and 3.5 parts of
triethylamine was added and mixed to carry out neutralization.
Further, 203.2 parts of water was added to disperse the mixture.
Then, 9.7 parts of a 40 wt % aqueous hexamethylenediamine solution
was added to the mixture, and chain-elongation reaction was carried
out. The product was heated under reduced pressure at 50.degree. C.
for 3 hours to remove MEK to obtain a polyurethane resin
dispersion.
Comparative Example 2
[0113] In a reaction device equipped with a stirrer and a heater
were charged 51.6 parts of "ETERNACOLL UH-200" (available from UBE
INDUSTRIES, LTD., a polycarbonate diol using 1,6-hexanediol and
dimethylcarbonate as starting materials and having a number average
molecular weight of 2000, an average hydroxyl group number: 2)
having a hydroxyl value of 56.1, 1.6 parts of trimethylolpropane,
5.1 parts of dimethylol propionic acid and 38.7 parts of MEK while
introducing nitrogen. Thereafter, the mixture was heated to
60.degree. C., and dissolution of dimethylol propionic acid was
confirmed. To the mixture were added 31.8 parts of hydrogen-added
MDI and 0.04 part of dibutyl tin dilaurate as a catalyst, and the
mixture was heated to 80.degree. C. to carry out urethanization
reaction over 4 hours to prepare a prepolymer. An NCO group content
at the time of completion of the urethanization reaction was 5.0 wt
%. After cooling the reaction mixture to 30.degree. C., 49.0 parts
of MEK was additionally added to the mixture, and 3.7 parts of
triethylamine was added and mixed to carry out neutralization.
Further, 194.8 parts of water was added to disperse the mixture.
Then, 9.6 parts of a 40 wt % aqueous hexamethylenediamine solution
was added to the mixture, and chain-elongation reaction was carried
out. The product was heated under reduced pressure at 50.degree. C.
for 3 hours to remove MEK to obtain a polyurethane resin
dispersion.
[0114] Number average molecular weights of polycarbonate polyols
prepared in Examples 1 to 6 and Comparative examples 1 to 2 are
shown in Table 1.
Test Example 1
Evaluation of Film Preparing Property
[0115] The above-mentioned respective polyurethane resin
dispersions were each coated on a glass plate with a thickness of
about 0.4 mm uniformly. Then, each was dried at 120.degree. C. for
3 hours, and film-forming property was evaluated with naked eyes.
The standard of the evaluation are .largecircle.: no crack was
found in the resulting film, .DELTA.: a little crack was found in
the resulting film, and X: cracks were found on the whole resulting
film
(Preparation of Polyurethane Film)
[0116] The above-mentioned respective polyurethane resin
dispersions were coated on a glass plate with a thickness of about
0.4 mm uniformly. Then, each was dried at 120.degree. C. for 3
hours, and peeled off from the glass plate, and applied to the
following evaluations.
(Physical Property of Film)
[0117] According to the method in accordance with JIS K 7113,
modulus of elasticity of the above-mentioned polyurethane films was
measured.
[0118] The film-forming property and modulus of elasticity of the
film are shown in Table 1.
TABLE-US-00001 TABLE 1 Example Example Example Example Example
Example Comparative Comparative 1 2 3 4 5 6 example 1 example 2
Number average 1650 700 830 1500 1900 890 2000 2000 molecular
weight of polycarbonate polyol Film-forming .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .DELTA. X property Modulus of 440 270 290 490 550 410
140 210 elasticity [MPa]
Example 7
Preparation of Polycarbonate Polyol (a1-7)
[0119] A trimethylolpropane-containing polycarbonate polyol (a
number average molecular weight 900, average hydroxyl group number
2.7) as Polycarbonate polyol (a1-7) was prepared as follows.
[0120] In 500 ml of a round-bottom flask made of a glass and
equipped with a fractionating column, a stirrer, a thermometer and
a nitrogen-introducing tube were charged 91.2 parts of
dimethylcarbonate, 134.2 parts of trimethylolpropane (available
from MITSUBISHI GAS CHEMICAL COMPANY INC.) and 0.1 part of
potassium carbonate, and transesterification reaction was carried
out for 3 hours under normal pressure and under stirring, while
removing a mixture of methanol and dimethylcarbonate by
distillation. During the procedure, the reaction temperature was
gradually raised from 85.degree. C. to 110.degree. C., and a
composition of the distillate was controlled so that it became an
azeotropic composition of methanol and dimethylcarbonate or a
neighbor thereof. Thereafter, the pressure was gradually reduced to
30 mmHg, and transesterification reaction was further carried out
at 120.degree. C. for 2 hours under stirring while removing a
mixture of methanol and dimethylcarbonate by distillation. After
completion of the reaction (after completion of distillation of
methanol and dimethylcarbonate), the reaction mixture was cooled to
room temperature to obtain a polycarbonate polyol prepolymer.
Incidentally, the transesterification reaction was carried out in a
nitrogen stream. The resulting polycarbonate polyol prepolymer had
a number average molecular weight of 500. Next, in 1000 ml of a
round-bottom flask made of a glass and equipped with a stirrer, a
thermometer, a nitrogen-introducing tube and a condenser were
charged 50.0 parts of the resulting polycarbonate polyol prepolymer
and 400 parts of a polycarbonate diol (available from UBE
INDUSTRIES, LTD., Trade name: ETERNACOLL UH-100, which uses
1,6-hexanediol and a carbonate as starting materials having a
molecular weight of 1000, a hydroxyl value: 112.2 mg KOH/g), and
the mixture was stirred under reduced pressure of 50 mmHg and after
reaching to the reaction temperature to 125.degree. C., the
reaction was carried out at 125.degree. C. for 4 hours. Sampling
was carried out in the course of the reaction, and it was confirmed
that the transesterification reaction reached to equilibrium by GPC
measurement. After completion of the reaction, the reaction mixture
was cooled to room temperature, and dissolved in 3000 parts of
ethyl acetate. 70 parts of water was added to the mixture, the
mixture was stirred for 30 minutes and the aqueous layer was
removed by separating the liquids. This operation was carried out
once more to obtain an ethyl acetate solution. To the ethyl acetate
solution was added 30 g of magnesium sulfate, and the mixture was
stirred for 30 minutes. Then, the mixture was filtered to remove
magnesium sulfate, and ethyl acetate was then removed by
distillation to obtain a trimethylolpropane-containing
Polycarbonate polyol (a1-7). The resulting Polycarbonate polyol
(a1-7) had a number average molecular weight of 900, and an average
hydroxyl group number of 2.7.
(Preparation of Aqueous Polyurethane Resin Dispersion)
[0121] In a reaction device equipped with a stirrer and a heater
were charged 15.0 parts by weight of "ETERNACOLL UH-200" (available
from UBE INDUSTRIES, LTD., a polycarbonate diol using
1,6-hexanediol and dimethylcarbonate as starting materials and
having a number average molecular weight of 2000, an average
hydroxyl group number: 2) having a hydroxyl value of 56.1, 3.8
parts by weight of the above-mentioned Polycarbonate polyol (a1-7),
1.5 parts by weight of dimethylol propionic acid (available from
NIPPON KASEI CHEMICAL CO., LTD.) and 13.0 parts by weight of methyl
ethyl ketone (hereinafter sometimes abbreviated to as "MEK"), while
introducing nitrogen. Thereafter, the mixture was heated to
60.degree. C., and dissolution of dimethylol propionic acid was
confirmed. To the mixture were added 9.7 parts by weight of
4,4'-dicyclohexylmethane diisocyanate (hereinafter sometimes
abbreviated to as "hydrogen-added MDI") and 0.01 part by weight of
dibutyl tin dilaurate as a catalyst, and the mixture was heated to
80.degree. C. to carry out urethanization reaction over 4 hours to
prepare a prepolymer (Step .alpha.). An NCO group content at the
time of completion of the urethanization reaction was 5.0 wt %.
After cooling the reaction mixture to 30.degree. C., 15.8 parts of
MEK was added to the mixture, and 1.0 part of triethylamine was
added and mixed to carry out neutralization (Step .beta.). Further,
61.5 parts of water was added to disperse the mixture (Step
.gamma.). Then, 2.8 parts of a 40 wt % aqueous hexamethylenediamine
solution was added to the mixture, and chain-elongation reaction
was carried out at 20.degree. C. for 60 hours (Step .delta.). The
product was heated under reduced pressure from 20.degree. C. to
50.degree. C. for 3 hours to remove MEK to obtain a polyurethane
resin dispersion.
Example 8
[0122] In a reaction device equipped with a stirrer and a heater
were charged 19.8 parts by weight of "ETERNACOLL UH-200" (available
from UBE INDUSTRIES, LTD., a polycarbonate diol using
1,6-hexanediol and dimethylcarbonate as starting materials and
having a number average molecular weight of 2000, an average
hydroxyl group number: 2) having a hydroxyl value of 56.1, 10.1
parts by weight of Polycarbonate polyol (a1-7) used in Example 1,
2.7 parts by weight of dimethylol propionic acid and 21.4 parts by
weight of MEK while introducing nitrogen. Thereafter, the mixture
was heated to 60.degree. C., and dissolution of dimethylol
propionic acid was confirmed. To the mixture were added 17.5 parts
by weight of hydrogen-added MDI and 0.02 part by weight of dibutyl
tin dilaurate as a catalyst, and the mixture was heated to
80.degree. C. to carry out urethanization reaction over 4 hours to
prepare a prepolymer (Step .alpha.). An NCO group content at the
time of completion of the urethanization reaction was 5.4 wt %.
After cooling the reaction mixture to 30.degree. C., 25.5 parts by
weight of MEK was added to the mixture, and 1.9 parts by weight of
triethylamine was added and mixed to carry out neutralization (Step
.beta.). Further, 100.5 parts of water was added to disperse the
mixture (Step .gamma.). Then, 5.6 parts of a 40 wt % aqueous
hexamethylenediamine solution was added to the mixture, and
chain-elongation reaction was carried out at 20.degree. C. for 48
hours (Step .delta.). The product was heated under reduced pressure
from 20.degree. C. to 50.degree. C. for 3 hours to remove MEK to
obtain a polyurethane resin dispersion.
Example 9
Preparation of Polycarbonate Polyol (a1-9)
[0123] A trimethylolpropane-containing polycarbonate polyol (a
number average molecular weight: 1650, average hydroxyl group
number: 2.8) as Polycarbonate polyol (a1-9) was prepared as
follows.
[0124] In 500 ml of a round-bottom flask made of a glass and
equipped with a fractionating column, a stirrer, a thermometer and
a nitrogen-introducing tube were charged 91.2 parts of
dimethylcarbonate, 134.2 parts of trimethylolpropane and 0.1 part
of potassium carbonate, and transesterification reaction was
carried out for 3 hours under normal pressure and under stirring,
while removing a mixture of methanol and dimethylcarbonate by
distillation. During the procedure, the reaction temperature was
gradually raised from 85.degree. C. to 110.degree. C., and a
composition of the distillate was controlled so that it became an
azeotropic composition of methanol and dimethylcarbonate or a
neighbor thereof. Thereafter, the pressure was gradually reduced to
30 mmHg, and transesterification reaction was further carried out
at 120.degree. C. for 2 hours under stirring while removing a
mixture of methanol and dimethylcarbonate by distillation. After
completion of the reaction (after completion of distillation of
methanol and dimethylcarbonate), the reaction mixture was cooled to
room temperature to obtain a polycarbonate polyol prepolymer.
Incidentally, the transesterification reaction was carried out in a
nitrogen stream. The resulting polycarbonate polyol prepolymer had
a number average molecular weight of 500. Next, in 1000 ml of a
round-bottom flask made of a glass and equipped with a stirrer, a
thermometer, a nitrogen-introducing tube and a condenser were
charged 15.0 parts of the resulting polycarbonate polyol prepolymer
and 200 parts of a polycarbonate diol (available from UBE
INDUSTRIES, LTD., Trade name. ETERNACOLL UH-200, molecular weight
2000, hydroxyl value: 56.1 mg KOH/g), and the mixture was stirred
under reduced pressure of 50 mmHg and after reaching to the
reaction temperature to 125.degree. C., the reaction was carried
out at 125.degree. C. for 4 hours. Sampling was carried out in the
course of the reaction, and it was confirmed that the
transesterification reaction reached to equilibrium by GPC
measurement. After completion of the reaction, the reaction mixture
was cooled to room temperature, and dissolved in 540 parts of ethyl
acetate. 100 parts of water was added to the mixture and after
stirring the mixture for 30 minutes, the aqueous layer was removed
by separating the liquids. This operation was carried out once more
to obtain an ethyl acetate solution. To the ethyl acetate solution
was added 50 g of magnesium sulfate and the mixture was stirred for
30 minutes. Then, the mixture was filtered to remove magnesium
sulfate, and ethyl acetate was then removed by distillation to
obtain a trimethylolpropane-containing Polycarbonate polyol (a1-9).
The resulting Polycarbonate polyol (a1-9) had a number average
molecular weight of 1650, and an average hydroxyl group number of
2.8.
(Preparation of Aqueous Polyurethane Resin Dispersion)
[0125] In a reaction device equipped with a stirrer and a heater
were charged 35.7 parts by weight of "ETERNACOLL UH-200" (available
from UBE INDUSTRIES, LTD., a polycarbonate diol using
1,6-hexanediol and dimethylcarbonate as starting materials and
having a number average molecular weight of 2000, an average
hydroxyl group number: 2) having a hydroxyl value of 56.1, 21.5
parts by weight of Polycarbonate polyol (a1-9), 4.8 parts by weight
of dimethylol propionic acid and 40.2 parts by weight of MEK while
introducing nitrogen. Thereafter, the mixture was heated to
60.degree. C., and dissolution of dimethylol propionic acid was
confirmed. To the mixture were added 31.5 parts by weight of
hydrogen-added MDI and 0.04 part by weight of dibutyl tin dilaurate
as a catalyst, and the mixture was heated to 80.degree. C. to carry
out urethanization reaction over 4 hours to prepare a prepolymer
(Step .alpha.). An NCO group content at the time of completion of
the urethanization reaction was 6.7 wt %. After cooling the
reaction mixture to 30.degree. C., 56.4 parts by weight of MEK was
added to the mixture, and 3.4 parts by weight of triethylamine was
added and mixed to carry out neutralization (Step .beta.). Further,
198.9 parts of water was added to disperse the mixture (Step
.gamma.). Then, 9.3 parts by weight of a 40 wt % aqueous
hexamethylenediamine solution was added to the mixture, and
chain-elongation reaction was carried out at 20.degree. C. for 48
hours (Step .delta.). The product was heated under reduced pressure
at 50.degree. C. for 3 hours to remove MEK to obtain a polyurethane
resin dispersion.
Example 10
[0126] In a reaction device equipped with a stirrer and a heater
were charged 67.0 parts of "ETERNACOLL UH-200" (available from UBE
INDUSTRIES, LTD., a polycarbonate diol using 1,6-hexanediol and
dimethylcarbonate as starting materials and having a number average
molecular weight of 2000, an average hydroxyl group number: 2)
having a hydroxyl value of 56.1, 4.0 parts of Polycarbonate polyol
(a1-7) used in Example 1, 5.0 parts of dimethylol propionic acid
and 37.0 parts of MEK while introducing nitrogen. Thereafter, the
mixture was heated to 60.degree. C., and dissolution of dimethylol
propionic acid was confirmed. To the mixture were added 30.0 parts
of hydrogen-added MDI and 0.04 part of dibutyl tin dilaurate as a
catalyst, and the mixture was heated to 80.degree. C. to carry out
urethanization reaction over 4 hours to prepare a prepolymer (Step
.alpha.). An NCO group content at the time of completion of the
urethanization reaction was 4.6 wt %. After cooling the reaction
mixture to 30.degree. C., 63.4 parts of MEK was added to the
mixture, and 3.5 parts of triethylamine was added and mixed to
carry out neutralization (Step .beta.). Further, 221.6 parts of
water was added to disperse the mixture (Step .gamma.). Then, 7.7
parts of a 40 wt % aqueous hexamethylenediamine solution was added
to the mixture, and chain-elongation reaction was carried out at
20.degree. C. for 48 hours (Step .delta.). The product was heated
under reduced pressure from 20.degree. C. to 50.degree. C. for 3
hours to remove MEK to obtain a polyurethane resin dispersion.
Test Example 2
[0127] Evaluation of the film-forming property was carried out in
the same manner as in Test example 1. The results are shown in
Table 2.
TABLE-US-00002 TABLE 2 Example Example Example Example Comparative
Comparative 7 8 9 10 example 3 example 4 Evaluation of
.largecircle. .largecircle. .largecircle. .largecircle. .DELTA. X
film-forming property
[0128] A polyurethane film was prepared in the same manner as in
Test example 1, modulus of elasticity and tensile elongation at
break of the above-mentioned polyurethane film was measured
according to the method in accordance with JIS K 7113. The results
are shown in Table 3.
TABLE-US-00003 TABLE 3 Example Example Example Example Comparative
Comparative 7 8 9 10 example 3 example 4 Modulus of 90 110 110 37
140 210 elasticity (MPa) Tensile 680 800 720 1000 620 470
elongation at break (%)
Example 11
Preparation of Coating Composition
[0129] 280 g of a water-dispersible polyester polyol ("SETAL 6306"
manufactured by NUPLEX CO., a resin concentration: 60% by weight, a
hydroxyl value: 89 mg KOH/g of resin, an acid value: 42 mg KOH/g of
resin) neutralized by dimethylethanolamine with a molar ratio of
carboxylic acid/amine being 1.0, 600 g of rutile type titanium
dioxide, 15 g of barium sulfate and 280 g of deionized water were
dispersed by a paint shaker for 30 minutes to prepare a
pigment-dispersed paste.
[0130] To the resulting pigment-dispersed paste were added 430 g of
the aqueous polyurethane resin dispersion obtained in Example 1,
115 g of a water-dispersible polyester polyol ("SETAL 6306"
manufactured by NUPLEX CO.) neutralized by dimethylethanolamine
with a molar ratio of carboxylic acid/amine being 1.0, deionized
water 115 g, 330 g of an acryl polyol ("SETALUX 1767VV-65"
manufactured by ACZO NOBEL, a number average molecular weight=2500,
a hydroxyl value=150 mg KOH/g (based on the resin component),
Tg=9.0.degree. C.), and 330 g of a methyl-butyl mixed etherified
melamine resin ("U-VAN 2028" manufactured by MITSUI CHEMICALS,
INC.), and the mixture was uniformly dispersed to obtain a coating
composition.
[0131] The resulting coating composition was coated onto an
electrodeposited steel plate with a thickness of 25 .mu.m, and
heated at 140.degree. C. for 30 minutes to obtain a good coating
film.
UTILIZABILITY IN INDUSTRY
[0132] The aqueous polyurethane resin dispersion of the present
invention can be widely utilized as a starting material for paint
or a coating agent, etc.
* * * * *